bluuebunny/crossref_metadata_2025 huggingface dataset:
THE MICROSTRUCTURE AND ITS HIGH-TEMPERATURE ANNEALING BEHAVIOURS OF a-Si∶O∶H FILM
Authors: WANG YONG-QIAN  , CHEN CHANG-YONG  , CHEN WEI-DE  , YANG FU-HUA  , DIAO HONG-WEI  , XU ZHEN-JIA  , ZHANG SHI-BIN  , KONG GUANG-LIN  , LIAO XIAN-BO  ,   (1)中国科学院半导体研究所超晶格与微结构国家重点实验室,北京100083; (2)中国科学院半导体研究所凝聚态物理中心,表面物理国家重点实验室北京100083
Published: December 2020

The microstructure and its annealing behaviours of a Si∶O∶H film prepared by PECVD are investigated in detail using micro Raman spectroscopy, X-ray photoelectron spectroscopy and Infrared absorption spectroscopy. The results indicate that the as deposited a-Si∶O∶H film is structural inhomogeneous, with Si-riched phases surrounded by O-riched phases. The Si-riched phases are found to be nonhydrogenated amorphous silicon (a-Si) clusters, and the O riched phases SiOx∶H ( x ≈1.35) are formed by random bonding of Si, O and H atoms. By high temperature annealing at 1150℃, the SiOx∶H ( x ≈1.35) matrix is shown to be transformed into SiO2 and SiOx (x ≈0.64), during which all of the hydrogen atoms in the film escape and some of silicon atoms are separated from the SiOx∶H ( x ≈1.35) matrix;The separated silicon atoms are found to be participated in the nucleation and growth processes of solid phase crystallization of the a Si-clusters, nano-crystalline silicon (nc-Si) is then formed. The microstructure of the annealed film is thereby described with a multi shell model, in which the nc- Si clusters are embedded in SiOx (x =0.64) and SiO2. The former is located at the boundaries of the nc-Si clusters, with a thickness comparable with the scale of nc-Si clusters, and forms the transition oxide layer between the nc-Si and the SiO2 matrix.
XPS AND AES INVESTIGATION OF GaN FILMS GROWN BY MBE
Authors: YUAN JIN-SHE  , CHEN GUANG-DE  , QI MING  , LI AI-ZHEN  , XU ZHUO  ,   (1)西安交通大学电子材料研究所,西安710049; (2)西安交通大学应用物理系,西安710049; (3)西安交通大学应用物理系,西安710049,西安理工大学应用物理系,西安710048; (4)中国科学院上海冶金研究所,上海200050
Published: December 2020

The surface composition of GaN grown by plasma-assisted MBE was investigated using X-ray photoelectron spectroscopy and Auger election emission spectroscopy(AES), while the depth profile was analyzed by AES with Ar iron sputtering. The experimental results indicated that unintentional doped semi-in salating films formed by plasma-assisted MBE had a rich-gallium surface. It was found that the impurity carbon was chiefly adsorbed onto the surface while oxygen diffused into the bulk to distribute in a certain depth. Consequently, the oxygen-related impurity band and an acceptor level could be simultaneously formed in the layer. This influenced the optical and electrical properties of the films.
C-V CHARACTERISTICS OF Bi2Ti2O7 THIN FILMS ON n-Si(100)
Authors: WANG SHAO-WEI  , LU WEI  , WANG HONG  , WANG DONG  , WANG MIN  , SHEN XUE-CHU  ,   (1)山东大学晶体材料国家重点实验室,济南250100; (2)中国科学院上海技术物理研究所,红外物理国家重点实验室上海200083; (3)中国科学院上海技术物理研究所,红外物理国家重点实验室上海200083,山东大学晶体材料国家重点实验室,济南250100
Published: December 2020

We report the growth of Bi2Ti2O7 thin films on n type Si substrates by the chemical solution decomposition technique. Both the X-ray double-crystal diffraction and atomic force micro spectroscopy measurements are used to check the film properties. It is shown that the film is a multi crystal film dominated by the Bi2Ti2O7 phase. The C-V measurements are also performed on Au/Bi2Ti2O7/n-Si(100) MOS structure. It is revealed that both the fixed and mobile negative charges are contained in the film. The mobile negative charge results in the hysteresis loops on C-V curve.
NONLINEARLY OPTICAL-INDUCED BIREFRINGENCE IN AZO LIQUID CRYSTAL POLYMERS
Authors: LIANG ZHONG-CHENG  , MING HAI  , WANG PEI  , ZHANG JIANG-YING  , LONG YUN-ZE  , XIA YONG  , XIE JIAN-PING  , ZHANG QI-JIN  ,   (1)中国科学技术大学物理系,合肥230026; (2)中国科学技术大学物理系,合肥230026,南京师范大学物理系,南京210097
Published: December 2020

We introduce the experimental results of nonlinearly optical induced birefringence in azo liquid crystal polymer P-CN. The nonlinear nature of the photochemical process in P-CN was verified by the use of Z scan technique. Based on the analysis of the photo isomerization mechanism, a nonlinearly optical method is proposed to induce the birefringence in azo liquid crystal polymers by optical optical isomerization cycle.
THE INFLUENCE OF InAs QUANTUM DOTS ON THE TRANSPORT PROPERTIES OF SCHOTTKY DIODE
Authors: LI HONG-WEI  , WANG TAI-HONG  ,   中国科学院物理研究所,北京100080
Published: December 2020

In the temperature range from 77 to 292 K, we investigated the transport properties of metal-semiconductor-metal diode containing InAs quantum dots. With increasing temperature, the current hysteresis loops, which were caused by charged quantum dots, reduced gradually. The resonant tunneling process, which may occur in some Schottky barriers, could induce steps on the I-V curves in the measured temperature range and diminish the hysteresis loops intensively. We have calculated the saturation current density and ideality factor of the Schottky barrier with reverse characteristics. We found that the resonant tunneling process would shift the Schottky barrier away from the ideality status, while the charging effect mainly influenced the barrier height and therefore influenced the saturation current density.
Unilaterally coupled synchronization of spatiotemporal chaos
Authors: Zhang Xu  , Shen Ke  ,   (1)长春理工大学理学院物理系,长春130022; (2)河北工业大学理学院应用物理系,天津300130;长春理工大学理学院物理系,长春130022
Published: December 2020

Based on a coupled map lattice model, we present an approach of unilateral coupling to implement the synchronization of spatiotemporal chaos. Our numerical simulations show that the two spatiotemporal systems can accurately become synchronized by appropriately selecting the coupling strength and the equilibrium coefficient. We calculate the largest conditional Lyapunov exponent，so as to give the minimum coupling strength that can achieve the synchronization，and the functional relationship between the minimum coupling strength and the system parameters. The simulation results also indicate that this method is robust against noise.
Nonlinear continuous predictive variable structure control and synchronization of chaotic systems
Authors: Liu Fu-Cai  , Wang Juan  , Shi Miao  , Gao Xiu-Wei  ,   (1)燕山大学电气工程学院,秦皇岛066004; (2)中国科学院大连化学物理研究所,大连116021
Published: December 2020

This paper presents a predictive variable structure control method for the control and synchronization of chaotic nonlinear dynamic systems based on a unified frame for both the control and the synchronization. Two controllers are designed. One is the predictive controller for nominal model, and the other is a variable structure controller for system perturbation. The tracking control of reference signal is realized, and the method has the merit of robustness of variable structure control. The effectiveness of the proposed method are proved by numerical simulations.
Grassberger-Procaccia algorithm for evaluating the fractal characteristic of strange attractors
Authors: Wang An-Liang  , Yang Chun-Xin  ,   北京航空航天大学飞行器设计与应用力学系,北京100083;
Published: December 2020

Based on the three general strange attractors generated by the Lorenz equation, the Rssler equation and the Hénon map, the Grassberger-Procaccia algorithm is analyzed. For a finite time series, the sampling number, delay time, embedding dimension and the length of scaling region affect the precision of evaluating the correlation dimension D—2 and the 2nd-order Kolmogorov entropy K—2 by G-P algorithm. In the analysis of the trend of a correlation integral, the impression for a continuous dynamical system is different from that of a discrete dynamical system in delay time and embedding dimension. The criterion of delay time chosen by mutual information is unnecessary for calculating the correlation dimension D—2. The applicable conditions for G-P algorithm is also indicated.
Pressure difference between inside and outside of a drop and its critical radius in dropwise condensation
Authors: Min Jing-Chun  ,   清华大学工程力学系传热强化与过程节能教育部重点实验室,北京100084
Published: December 2020

It was proved using the thermodynamic method that the pressure difference between the inside and outside of a liquid drop sitting on a solid surface follows the classical Laplace equation, and this was further validated using the mechanics method. Such a pressure difference depends only on the surface tension of the liquid and the radius of the drop but is independent of the liquidsolid contact angle.Similarly, the critical radius of a drop in dropwise condensation is also independent of the contact angle and can be calculated using the classical Kalvin equation.
Output characteristics of tunable fiber ring-laser:modeling and experimentation
Authors: Dong Xin-Yong  , Zhao Chun-Liu  , Guan Bai-Ou  , Tan Hua-Yao  , Yuan Shu-Zhong  , Kai Gui-Yun  , Dong Xiao-Yi  ,   (1)南开大学现代光学研究所,天津300071; (2)南开大学现代光学研究所,天津300071;香港理工大学电机工程系,香港九龙; (3)香港理工大学电机工程系,香港九龙
Published: December 2020

Output characteristics of a tunable fiber ring laser are studied both by theoretical modeling and by experimentation. Dependencies of laser output power on lasing wavelength, pump power, erbiumdoped fiber (EDF) length, output coupling ratio, and intracavity loss are demonstrated by using a simple theoretical model. It is shown that a wide tunable range over 130nm (i.e.1500—1630nm) can be obtained through parameter optimization. As a result, the laser with a tunable range up to 100nm, high output power, and high signaltonoise ratio in most of the tunable range has been achieved in experimentation. The experimental data are in good agreement with the theoretical modeling results.
The influence of the ratio of seed to pump energy on Brillouin amplification*
Authors: Ding Ying-Chun  , Lv Zhi-Wei  , He Wei-Ming  ,   哈尔滨工业大学光电子技术研究所,哈尔滨150001
Published: December 2020

Brillouin amplifier was numerically simulated by using the theoretic model of transient stimulated Brillouin scattering. Wehave oblained the depleted pump energy extract efficiency, Stokes seed amplification factor, seed beam pulse\|width compression ratio and pump beam pulse\|width compression ratio versus the ratio of seed to pump energy. Experiment was done so as to verify the theory. The theoretical calculation was in good agreement with experimental results.
Ｔｈｅｅｆｆｅｃｔｏｆｄｏｐｅｄ Ｚｎｏｎｔｈｅｌｏｗ ｔｅｍｐｅｒａｔｕｒｅｐｒｏｐｅｒｔｉｅｓｏｆｈｅａｖｙｅｌｅｃｔｒｏｎｃｏｍｐｏｕｎｄｓＣｅＣｕ6 -ｘＺｎｘ
Authors: Meng Ji-Bao  , Chen Zhao-Jia  , Luo Jian-Lin  , Bai Hai-Yang  , Wang Nan-Lin  , Wang Yu-Peng  ,   (1)中国科学院理化技术研究所,北京100080;中国科学院物理研究所极端条件物理实验室,北京100080;中国科学院研究生院北京100039; (2)中国科学院物理研究所极端条件物理实验室,北京100080
Published: December 2020

Ｗｅｒｅｐｏｒｔｔｈｅｐａｒｔｉｃｕｌａｒｓａｍｐｌｅｐｒｅｐａｒａｔｉｏｎｍｅｔｈｏｄａｎｄｔｈｅｅｘｐｅｒｉｍｅｎｔａｌｒｅｓｕｌｔｓｏｆｔｈｅｌｏｗ ｔｅｍｐｅｒａｔｕｒｅｒｅｓｉｓｔａｎｃｅａｎｄｓｐｅ ｃｉｆｉｃｈｅａｔｏｆｈｅａｖｙｅｌｅｃｔｒｏｎｍｅｔａｌｓＣｅＣｕ6 -ｘＺｎｘ(ｘ=0 .0 5,0 .1 0 ,0 .1 5,0 .2 0 ,0 . 3 0 ) .ＴｈｅｐｈｙｓｉｃａｌｏｒｉｇｉｎｆｏｒｔｈｅｅｆｆｅｃｔｏｆｔｈｅＺｎｃｏｎｔｅｎｔｏｎｔｈｅｌｏｗ ｔｅｍｐｅｒａｔｕｒｅｐｒｏｐｅｒｔｉｅｓｏｆＣｅＣｕ6 -ｘＺｎｘａｒｅｓｔｕｄｉｅｄ.ＷｅｆｉｎｄｔｈａｔｂｏｔｈｔｈｅｃｏｅｆｆｉｃｉｅｎｔｃｏｆＫｏｎｄｏｓｃａｔｔｅｒｉｎｇｔｅｒｍａｎｄｔｈｅＴｍａｘｃｏｒｒｅｓｐｏｎｄｉｎｇｔｏｔｈｅｍａｘｉｍａｌｒｅｓｉｓｔａｎｃｅｄｅｃｒｅａｓｅｓｗｉｔｈｉｎｃｒｅａｓｉｎｇＺｎｃｏｎｔｅｎｔ.ＷｈｉｌｅｔｈｅＤｅｂｙｅｔｅｍｐｅｒａｔｕｒｅｏｆＣｅＣｕ6 -ｘＺｎｘｓｌｉｇｈｔｌｙｇｏｕｐｗｉｔｈｉｎｃｒｅａｓｉｎｇＺｎｃｏｎｔｅｎt.
Ｔｈｅｒｍｏｅｌｅｃｔｒｉｃｐｒｏｐｅｒｔｉｅｓｏｆｎ ｔｙｐｅＢａｙＮｉｘＣｏ4-ｘＳｂ1 2
Authors: Tang Xin-feng  , Chen Li-Dong  , T Goto  , T Hiral  , Yuan Run-Zhang  ,   (1)日本东北大学金属材料研究所,仙台980-8577,日本; (2)上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室,上海200050; (3)武汉理工大学材料复合新技术国家重点实验室,武汉430070
Published: December 2020

ＥｆｆｅｃｔｓｏｆＢａｆｉｌｌｉｎｇｆｒａｃｔｉｏｎａｎｄＮｉｃｏｎｔｅｎｔｏｎｔｈｅｔｈｅｒｍｏｅｌｅｃｔｒｉｃｐｒｏｐｅｒｔｉｅｓｏｆｎ ｔｙｐｅＢａｙＮｉｘＣｏ4-ｘＳｂ1 2 (ｘ =0— 0.1 ,ｙ=
0— 0.4)ｗｅｒｅｉｎｖｅｓｔｉｇａｔｅｄ .ＴｈｅｒｍａｌｃｏｎｄｕｃｔｉｖｉｔｙｄｅｃｒｅａｓｅｄｗｉｔｈｉｎｃｒｅａｓｉｎｇＢａｆｉｌｌｉｎｇｆｒａｃｔｉｏｎａｎｄｔｅｍｐｅｒａｔｕｒｅ.Ｗｈｅｎｙｗａｓｆｉｘｅｄａｔ0 .3 ,ｔｈｅｔｈｅｒｍａｌｃｏｎｄｕｃｔｉｖｉｔｙｄｅｃｒｅａｓｅｄｗｉｔｈｉｎｃｒｅａｓｉｎｇＮｉｃｏｎｔｅｎｔ,ａｎｄｒｅａｃｈｅｄａｍｉｎｉｍｕｍｖａｌｕｅａｔａｂｏｕｔｘ=0 . 0 5.ＬａｔｔｉｃｅｔｈｅｒｍａｌｃｏｎｄｕｃｔｉｖｉｔｙｄｅｃｒｅａｓｅｄｗｉｔｈｉｎｃｒｅａｓｉｎｇＮｉｃｏｎｔｅｎｔ,ｍｏｎｏｔｏｎｉｃａｌｌｙ (ｙ≤ 0 .1 ) .Ｅｌｅｃｔｒｏｎｃｏｎｃｅｎｔｒａｔｉｏｎａｎｄｅｌｅｃｔｒｉ ｃａｌｃｏｎｄｕｃｔｉｖｉｔｙｉｎｃｒｅａｓｅｄｗｉｔｈｉｎｃｒｅａｓｉｎｇＢａｆｉｌｌｉｎｇｆｒａｃｔｉｏｎａｎｄＮｉｃｏｎｔｅｎｔ.ＳｅｅｂｅｃｋｃｏｅｆｆｉｃｉｅｎｔｄｅｃｒｅａｓｅｄｗｉｔｈｉｎｃｒｅａｓｉｎｇＢａｆｉｌｌ ｉｎｇｆｒａｃｔｉｏｎａｎｄＮｉｃｏｎｔｅｎｔ.ＴｈｅｍａｘｉｍｕｍＺＴｖａｌｕｅｏｆ1 .2ｗａｓｏｂｔａｉｎｅｄａｔａｂｏｕｔ90 0Ｋｆｏｒｎ ｔｙｐｅＢａ0 . 3 Ｎｉ0 . 0 5Ｃｏ3 . 95Ｓｂ1 2
Ａｕｎｉｆｉｅｄｍｏｄｅｌｆｏｒ 1 ｆｎｏｉｓｅａｎｄ 1 ｆ2 ｎｏｉｓｅｄｕｅｔｏｅｌｅｃｔｒｏｍｉｇｒａｔｉｏｎｉｎｍｅｔａｌｆｉｌｍ
Authors: Du Lei  , Zhuang Yi-Qi  , Xue Li-Jun  ,   西安电子科技大学,西安710071
Published: December 2020

Ｂａｓｅｄｏｎｔｈｅｃｏｎｃｅｐｔｏｆｆｒｅｅｖｏｌｕｍｅｉｎｇｒａｉｎｂｏｕｎｄａｒｙ ,ａｕｎｉｆｉｅｄｍｏｄｅｌｆｏｒ1 ｆｎｏｉｓｅａｎｄ 1 ｆ2 ｎｏｉｓｅｉｎｍｅｔａｌｆｉｌｍｉｓｐｒｏ
ｐｏｓｅｄ.Ｉｔｉｓｓｈｏｗｎｆｒｏｍｔｈｅｍｏｄｅｌｔｈａｔｔｈｅｎｏｉｓｅｉｎｔｈｅｍｅｔａｌｆｉｌｍｗｉｔｈｐｅｒｆｅｃｔｐｏｌｙｃｒｙｓｔａｌｌｉｎｅｓｔｒｕｃｔｕｒｅａｐｐｅａｒｓｔｏｂｅ 1 ｆｔｙｐｅ,ｗｈｉｌｅ 1 ｆ2 ｃｏｍｐｏｎｅｎｔｉｓｉｎｔｒｏｄｕｃｅｄｗｈｅｎｔｈｅｆｉｌｍｉｓｓｕｂｊｅｃｔｅｄｔｏａｃｅｒｔａｉｎｅｌｅｔｒｏｍｉｇｒａｔｉｏｎｓｔｒｅｓｓａｎｄｔｈｅｖｏｉｄｓｔｈｕｓｉｎｄｕｃｅｄ.Ｉｔｉｓｏｂｓｅｒｖｅｄｉｎｔｈｅｅｌｅｃｔｒｏｍｉｇｒａｔｉｏｎｓｔｒｅｓｓｔｅｓｔｃｏｎｄｕｃｔｅｄｂｙｐｒｅｓｅｎｔａｕｔｈｏｒｓｔｈａｔγｉｓ1 0ｏｒｓｏｆｏｒｔｈｅｍｅａｓｕｒｅｄ 1 ｆγ ｎｏｉｓｅｉｎｔｈｅｍｅｔａｌｆｉｌｍｉｎｔｈｅｉｎｉｔｉａｌｓｔａｇｅｓｏｆｔｈｅｔｅｓｔ,ｂｕｔγａｂｒｕｐｔｌｙｉｎｃｒｅａｓｅｄｔｏｏｖｅｒ1 6ａｓｓｏｏｎａｓｔｈｅｖｏｉｄｓａｒｅｆｏｒｍｅｄ .Ｔｈｉｓａｇｒｅｅｓｗｉｔｈｔｈｅｐｒｅｄｉｃｔｉｏｎｏｆｔｈｅｄｅｖｅｌｏｐｅｄｍｏｄｅｌ.
ＴｈｅｍａｇｎｅｔｏｃｒｙｓｔａｌｌｉｎｅａｎｉｓｏｔｒｏｐｙｏｆＥｒ3 Ｇａ5Ｏ1 2ｕｎｄｅｒｈｉｇｈｍａｇｎｅｔｉｃｆｉｅｌｄ
Authors: Wang Wei  , Zhang Xi-Juan  , Yang Cui-Hong  , Cheng Hai-Ying  ,   扬州大学理学院物理系扬州大学复杂性科学中心,扬州225002
Published: December 2020

Ｍａｇｎｅｔｉｚａｔｉｏｎｉｓｃａｌｃｕｌａｔｅｄａｔ4 2Ｋｕｎｄｅｒａｈｉｇｈｍａｇｎｅｔｉｃｆｉｅｌｄｕｓｉｎｇｑｕａｎｔｕｍｔｈｅｏｒｙｗｈｅｎｔｈｅｍａｇｎｅｔｉｃｆｉｅｌｄｉｓａｐｐｌｉｅｄ
ｐａｒａｌｌｅｌｔｏ[0 0 1 ],[1 0 0 ],[1 1 0 ]ａｎｄ [1 1 1 ]ｄｉｒｅｃｔｉｏｎｓ.Ａｓｔｒｏｎｇａｎｉｓｏｔｒｏｐｙｏｆｍａｇｎｅｔｉｚａｔｉｏｎｉｓｏｂｓｅｒｖｅｄ .Ａｔｌｏｗｔｅｍｐｅｒａｔｕｒｅ,ｔｈｅｍａｇｎｅｔｉｚａｔｉｏｎｉｓａｌｉｎｅａｒｆｕｎｃｔｉｏｎｏｆｔｈｅｍａｇｎｅｔｉｃｆｉｅｌｄａｐｐｌｉｅｄｗｈｅｎｔｈｅｆｉｅｌｄｉｓｗｅａｋ
The new doubly-periodic solutions for nonlinear coupled scalar field equations( Ⅱ)
Authors: Li De-Sheng  , Zhang Hong-Qing  ,   (1)大连理工大学应用数学系，大连  116024; (2)大连理工大学应用数学系，大连  116024;沈阳工业大学理学院，沈阳  110023
Published: December 2020

Based on an ordinary differential equation which possesses doubly-periodic solut ions, a new method for constructing doubly-periodic solutions for differential e quations and its algorithm are proposed. This method can be carried out in compu ter by the aid of symbolic computation. A lot of new exact solutions of the nonl inear coupled scalar field equations are found by using this method.
Extracting information signal under noise by stochastic resonance
Authors: Zhu Heng-Jiang  , Li Rong  , Wen Xiao-Dong  ,   (1)北京师范大学物理系,北京  100875; (2)新疆师范大学数理信息学院,乌鲁木齐  830054
Published: December 2020

There are many reports on extracting the single frequency signal under noise by the stochastic resonance, but in which the information that the signal carries is zero. The experimental investigation in this paper manifests, when it is driven by an amplitude modulation wave and white noise, not only that the output of nonlinear bistable system exhibits the stochastic resonance phenomenon, but also that the modulation signal (information signal) can be extracted from the output by detecting and filtering. As compared with that from the electronics system by detecting and filtering direct the signal-to-noise(SNR) of modulation signal f rom the nonlinear bistable system is higher. Under the condition of adiabatic ap proximation the analytical formulation of the SNR of modulation signal is provid ed.
Dynamical behaviour of a cellular neural network
Authors: Wang Hong-Xia  , He Chen  ,   上海交通大学电子工程系,上海  200030
Published: December 2020

This paper studies mainly the dynamical behaviour of a cellular neural network. The dynamical property is controlled via adjusting the weight parameters of the system. The results indicate the structure of the attractor depends sensitively on the alteration of a parameter, and the dynamical behaviour of the cellular neural network shows the chaotic attractor with a larger extent of parameters.
A study on an improved Nagel-Schreckenberg traffic flow model with open boundary conditions
Authors: Bai Ke-Zhao  , Tan Hui-Li  , Liu Mu-Ren  , Kong Ling-Jiang  ,   广西师范大学物理与电子科学系,桂林  541004
Published: December 2020

For the improved Nagel-Schreckenberg model, we study it with an open boundary c ondition. We analyze the influence of the boundary condition,safety distance and deceleration probability on the traffic flow.
The possibility for realizing dropwise condensation with small contact angle
Authors: Cao Zhi-Jue  , Xia Bo-Li  , Zhang Yun  ,   (1)湖南师范大学理学院物理系，长沙  410081; (2)湖南师范大学理学院物理系，长沙  410081;中南大学能源与动力工程学院，长沙  410083
Published: December 2020

In this paper we analyze the variation in the chemical potential of the liquid d roplets at the critical state and the condensation that follows, and discuss the mechanism of mixed condensation. It is proved that there is a possibility of re alizing dropwise condensation with small contact angle when the super cooling of the condenser surface reduces and the dropoff radius of the droplet on the surf ace reaches a small value through certain appropriate methods.
Soft-x-ray emission from Ar clusters irradiated by 150fs laser pulses
Authors: Cheng Yuan-Li  , Zhao Yong-Peng  , Xiao Yi-Fan  , Xia Yuan-Qin  , Chen Jian-Xin  , Wang Qi  ,   哈尔滨工业大学可调谐激光技术国家级重点实验室,哈尔滨  150001
Published: December 2020

Soft x-ray emission from Ar clusters irradiated by intense 150 fs laser pulses a t an intensity of～5×1015 W/cm2 has been measured with a flat field spe ctrometer. Strong transitions from ArⅧ charge states have been observed, some s pectral lines belong to ArⅫ and ArⅩⅢ. Compared with optical field ionization, the interaction of intense laser pulse with clusters enhances drastically the a bsorption of laser energy and higher charge states are obtained as well. The sig nificant change in the spectrum is attributed to the collisinal heating of small -sized Ar clusters formed at on enough baking pressure of gas.
Kinoform-based iterative random phase encryption
Authors: Liu Fu-Min  , Zhai Hong-Chen  , Yang Xiao-Ping  ,   (1)教育部光电信息技术科学重点实验室，南开大学现代光学研究所，天津  300071; (2)天津理工学院光电信息与电子工程系，天津  300191
Published: December 2020

We propose a kinoform-based iterative random phase encryption method, in which t he phase retrieval algorithm is divided into two steps: 1) random phase encrypti on and 2) iteration solving for phase distributions of both the key phase plate and the kinoform. Since the iterations are executed between a Fourier spectrum a nd the kinoform, the decryption errors can be effectively depressed. By the quan tization process for the phase distributions during the iterations, a method of increasing the abundance of design is used to depress the decryption errors. The simulation results are presented at the end, which agree well with the theoreti cal analysis.
1.34μm Nd:YVO4 laser end-pumped by a diode-laser with flat-concave cavity type
Authors: Shang Lian-Ju  ,   曲阜师范大学物理系，曲阜  273165
Published: December 2020

The parameters of 1.34μm Nd:YVO4 flat-concave cavity laser with an end-pumped mode are theoretically analyzed.The operation of 1.34μm Nd:YVO4 flat-concave cavity laser end-pumped by a diode-laser is achieved.
The effect of collision on stimulated Raman scattering
Authors: Peng Zhong-Lin  , Zhu Shao-Ping  ,   (1)北京应用物理与计算数学研究所，北京  100088; (2)中国工程物理研究院研究生部，北京 8009信箱，北京  100088
Published: December 2020

Starting from kinetic equations,we discussed stimulated Raman scattering(SRS)by including both Landau damping(LD) and the collisional damping(CD).It was found that the linear growth rate of SRS is reduced substantially due to LD and CD.SRS can occur only for a region determined by both electron temperature and density .Gap in the spectrum corresponding to Raman scattering can be explained by the p resent model.
Moiré fringes of HOPG and mica in scanning probe microscopy
Authors: Guo Hai-Ming  , Liu Hong-Wen  , Wang Ye-Liang  , Xie Hui-Min  , Dai Fu-Long  , Gao Hong-Jun  ,   (1)清华大学工程力学系，北京  100084; (2)中国科学院物理研究所纳米物理与器件实验室，北京  100080
Published: December 2020

A Moiré technique using a scanning probe microscope (SPM) is developed, in which the natural periodic structure of a crystal is used as an ideal spacing grating. Formation principle of the SPM moiré fringes is discussed. Moiré patterns formed on highly oriented pyrolytic graphite (HOPG) and mica are investigated experimentally with STM and AFM, respectively. The results demonstrate the feasibility of the SPM Moiré technique in studying deformation and defects of crystals at the nanometer scale.
A study on the photo-induced crystallization properties in Au+-doped silicate glasses
Authors: Zeng Hui-Dan  , Qu Shi-Liang  , Jiang Xiong-Wei  , Qiu Jian-Rong  , Zhu Cong-Shan  , Gan F u-Xi  ,   中日合作“Photon Craft Project ”实验室,中国科学院上海光学精密机械研究所,上海   201800
Published: December 2020

We report the photo-induced crystallization behaviour of Au+-doped silicate glasses fabricated by Ti: sapphire femtosecond pulsed laser and successive heat treatment. Absorption spectra showed gold nanoparticles precipitated near the f ocal point of the laser beam. We also demonstrate that the size distribution of nanoparticles can be controlled by the laser irradiation conditions. Gold nanop articles-doped glasses reveal stronger optical limiting effects for nano-second laser pulses, and optical nonlinearities of the composite glass were also affec ted by laser irradiation conditions.
The simulation study of the tunneling effect in the breakdown of 4H-SiC pn junc tion diode
Authors: Lü Hong-Liang  , Zhang Yi-Men  , Zhang Yu-Ming  ,   西安电子科技大学微电子所，西安  710071
Published: December 2020

Based on the material data of 4H-SiC, we present a breakdown model for 4H-SiC pn junction diode, which includes both the avalanche impact ionization and the ban d-to-band tunneling. With this model, the influence of tunneling on the breakdow n characteristics of the devices is analyzed. The breakdown mechanism at differe nt temperatures and doping concentrations is explained, and the simulation resul ts can give a nice description for the breakdown characteristics of real devices .
A study on spin-polarized transport properties in magnetic-electric barrier st ructures
Authors: Qin Jian-Hua  , Guo Yong  , Chen Xin-Yi  , Gu Bing-Lin  ,   清华大学物理系，北京  100084
Published: December 2020

We investigated spin-polarized transport properties for electrons tunneling through a few of magnetic-electric barrier structures.The general formula of the transmission was derived.The relationship between the spin-polarization and the distribution of the nonhomogeneous magnetic field was revealed.Furthermore,our results also indicated that the spin-filtering effect can be enhanced significantly when a semiconductor with a larger g factor is used.
A study of the growth and optical properties of AlInGaN alloys
Authors: Huang Jin-Song  , Dong Xun  , Liu Xiang-Lin  , Xu Zhong-Ying  , Ge Wei-Kun  ,   (1)香港科技大学物理系，中国 香港; (2)中国科学院半导体研究所,北京  100083
Published: December 2020

We have studied the growth and optical properties of AlInGaN alloys in this arti cle. By the measurement of three samples, we found that the incorporation of In decreases with the increase of temperature, while there is nearly no change for the incorporation of Al. The sample grown at the lowest temperature had the best material and optical properties, which owes to the high In component, because t he In component can reduce defects and improve the material quality. We also use d the time_resolved photoluminescence(PL) to study the mechanism of recombinatio n of carriers, and found that the time dependence of PL intensity was not in exp onential decay, but in stretched_exponential decay. Through the study of the cha racter of this decay, we come to the conclusion that the emission comes from the recombination of localized excitons. Once more, this localization exhibites the character of quantum dots, and the stretched_exponential decay results from the hopping of carriers between different localized states. In addition, we have u sed the relation of emission energy dependence of carrier's lifetime and the cha racter of radiative recombination and non_radiative combination to confirm our c onclusion.
Studies of broadband yellow luminescence of GaN
Authors: Lai Tian-Shu  , Fan Hai-Hua  , Liu Zhen-Dong  , Lin Wei-Zhu  ,   中山大学光电材料与技术国家重点实验室，物理系，广州  510275
Published: December 2020

The broadband yellow luminescence(BYL) of undoped GaN film is fitted optimally by the linear superposition of multiple Gaussian functions by using nonlinear optimization technique. It is found that the BYL may be divided into the three Gauss_type spectra. It shows for the first time that the BYL originates from the combination of three independent radiative transitions. The energy levels of the initial states of the three independent transitions are measured directly in experiment by means of a novel absorption_normalized photoluminescent excitation spectroscopy. It is found that the three independent transitions have the same initial state but different final states. The origins of the initial and final states are assigned reasonably.
The solution of the Fokker-Planck equation of non-degenerate parametric amplific ation system for generation of squeezed light
Authors: Zhao Chao-Ying  , Tan Wei-Han  , Guo Qi-Zhi  ,   上海大学物理系,上海  200436
Published: December 2020

In this paper, we present the analytical solution of the Fokker-Planck equation of non-degenerate optical parametric amplification(NOPA)for generation of squeezed light. The maximum intra-cavity compression of squeezed light derived from the analytical solution is 1/16(vacuum fluctuations 1/4). To compare it with that of the previous result 1/8 of degenerate optical parametric amplification(DOPA), it seems that the squeezing for NOPA is superior to the squeezing for DOPA.
Boundary correlation functions of the six-vertex model with open boundary
Authors: Wang Yan-Shen  ,   西安交通大学应用物理系，西安  710049
Published: December 2020

The six-vertex model with open boundary conditions is discussed.The correlation functions for the model are calculated and expressed as some determinants.
Border collision bifurcations and chaos in a class of piecewise smooth systems w ith two boundaries
Authors: Dai Dong  , Ma Xi-Kui  , Li Xiao-Feng  ,   西安交通大学电气工程学院，西安  710049
Published: December 2020

A class of piecewise smooth maps with three zones is derived to describe the dynamics of a current-programmed Buck-Boost converter operating in a discontinuous mode. The numerical simulation is carried out and the bifurcation diagrams w ith the input voltage as a parameter are obtained. It is shown that, when a bifu rcation occurs, some eigenvalues of the Jacobian matrix jumps over the unit circ le in a discontinuous way, and there are always some orbit points lying on the b oundaries which separate different regions in the phase plane. It is concluded t hat border collision bifurcations could occur when the input voltage varies, for example, a bifurcation from a periodic orbit to another periodic orbit or chaot ic orbit.
The study of two-dimensional growth interface in Kuramoto-Sivashinsky and Karda- Parisi-Zhang models
Authors: Qi Hong-Ji  , Huang Li-Hua  , Shao Jian-Da  , Fan Zheng-Xiu  ,   中国科学院上海光学精密机械研究所，上海  201800
Published: December 2020

We have studied the evolution of (2+1)-dimensional surface morphology in the Kur amoto-Sivashinsky (K-S) and Karda-Parisi-Zhang (KPZ) models by using the numeric al simulation approach. The results show that the surface morphology has the sel f-affine fractal properties in both the models and exhibits a cellular structure after long-time growth in K-S model. With numerical correlation, dynamic scalin g characteristics are observed explicitly in both models, and the roughness expo nent, the growth exponent and the dynamic exponent are all obtained. From the si mulation results we suggest that the two models have the different properties in present time and space scale, and are not in the same universality class.
Dynamical phase transition and self-organized critical phenomena in the two-dim ensional gas lattice model
Authors: Gong Long-Yan  , Tong Pei-Qing  ,   南京师范大学物理科学与技术学院,南京  210097
Published: December 2020

A renovated Manna model is studied by computer simulation. The dynamic behavior of the system is changed evidently with the density of particle number.There is a critical particle number density (PND)ρc≈0.684… and critical exp onent α=0.452±0.02 at this density. Self-organized critical phenomena occur only at certain ranges of PND.
Focal switch of Hermite-Gaussian beams
Authors: Peng Run-Wu  , Lü Bai-Da  ,   (1)四川大学激光物理与化学研究所，成都  610064; (2)四川大学激光物理与化学研究所，成都  610064;华中科技大学激光技术国家重点实验室，武汉  430074
Published: December 2020

A simple optical system consisting of an aperture and a thin lens is considered.It is shown that when a Hermite-Gaussian (H-G) beam is incident on such a type of system and the parameters of the optical system and the beam satisfy a certain condition,a new effect called the focal switch can take place.Detailed numerical results and physical explanation are given to illustrate the characteristics of the focal switch of H-G beams.A comparison with the previous work is made and the potential application of the focal switch is pointed out.
The study of waveguide mode and dispersion property in photonic crystal fibres
Authors: Li Shu-Guang  , Liu Xiao-Dong  , Hou Lan-Tian  ,   (1)大连民族学院机电信息工程系，大连  116600; (2)燕山大学红外光纤与传感研究所，秦皇岛  066004
Published: December 2020

Based on a scalar approximation, the waveguide mode and dispersion property of photonic crystal fibres (PCFs) are investigated with an effective index approach in this paper. It is found that photonic crystal fibres can be single-mode over a very broad spectral range by changing PCFs cladding air-filling fraction or pitch of holes or core diameter. Designing of PCFs can yield zero dispersion at wa velength shorter than 1.27μm and nearly zero flattened dispersion over a very b road spectral range and dispersion compensation with a large normal dispersion.
Impact on the signal degree of polarization due to polarization mode dispersion in optical fibres
Authors: Wang Mu-Guang  , Li Tang-Jun  , Jian Shui-Sheng  ,   北方交通大学光波技术研究所，北京  100044
Published: December 2020

Using a compact optical link transmission model, the degradation of signal degre e of polarization (DOP) induced by polarization mode dispersion (PMD), especiall y the second-order PMD, and the input signal state of polarization in high-speed optical fibre communication systems is studied in detail. It is pointed out tha t the signal DOP can be used as the feedback control signal in the optical adapt ive first-order PMD optimal compensation systems compatibly. However, if the sec ond-order PMD is considered, the control algorithm will be complicated, and ther e will be the possibility that the system is trapped in a local optimum which wo uld downgrade compensator the performance.
Propagation of pulses obtained by modulating spatial optical solitons in planar optical waveguide
Authors: Liu Shan-Liang  ,   聊城大学光通信研究所,聊城  252059
Published: December 2020

Evolution of pulses obtained by modulating spatial optical solitons in a Kerr no nlinearity planar waveguide with anomalous dispersion is investigated. The pulse s will collapse, self_trapping or divergence according as its initial temporal w idth is more than, equal to or less than the critical value. The higher the orde r of the spatial soliton pulses, the smaller the critical value. The pulse colla pses fastest when its initial temporal width is equal to a special value, and th e more the difference between its initial temporal width and the special value, the slower it collapses. The higher the order of the spatial soliton pulses, th e smaller the special value. The peak power density, temporal and spatial width of the self_trapped pulses differ distinctly from their initial values
Intermediate mass dilepton production in a chemically non-equilibrated quark-glu on matter
Authors: He Ze-Jun  , Long Jia-Li  , Ma Guo-Liang  , Ma Yu-Gang  , Zhang Jia-Ju  , Liu Bo  ,   (1)中国科学院高能物理研究所，北京  100039; (2)中国科学院上海原子核研究所，上海  201800; (3)中国科学院上海原子核研究所，上海  201800;中国科学院近代物理研究所兰州重离子加速器国家实验室理论核物理中心，兰州   730000
Published: December 2020

We have studied dilepton production during the chemical equilibration of baryon_rich quark_gloun matter, and found that due to the slowing down of the cooling rate and the high initial temperature of the quark_gloun matter(QGM) produced at RHIC energies, the quark phase contribution to dileptons with intermediate mass es is significantly heightened, thus, the enhancement of dileptons with intermed iatc masses should be an signal for the QGM formation. Since this enhancement ca n compensate the dilepton suppression caused by increasing the initial chemical potential, therefore, the dilopton suppression may not be a signal for the quar k_gloun matter formation.
Simulated annealing method for powder diffraction pattern decomposition
Authors: Guo Li-Ping  , Cheng Zhi-Xu  , Han Fu-Tian  , Liu Yi  , Zhao Zhi-Xiang  ,   (1)广东省测试分析研究所，广州  510070; (2)中国原子能科学研究院核物理研究所，北京  102413
Published: December 2020

Simulated annealing algorithm was applied in the decomposition of neutron and x_ray powder diffraction pattern. The method described in this paper has two main advantages: first, the pattern decomposition results do not depend on the starting peak parameters, thus the difficulty in the choice of initial solutions, which occurs in fitting a complex pattern composed of severely overlapped peaks by a conventional least_squares profile fitting method, is overcome; secondly, it has the ability of searching for global other than local optimal solutions, thus can effectively resolve the multi_solution problem mathematically, and this advantage is the most useful when decomposing complex patterns with several local optimal solutions. The computing step is described in detail, the setting of relative parameters is discussed, and the simulated annealing method is compared with a conventional least_squares profile fitting method through both simulated pattern and actual pattern to demonstrate its unique advantage in the decomposition of complex pattern. In principle, the method can also be applied in other kinds of spectra which can be described by profile shape function.
The quantization of a mesoscopic dissipation transmission line
Authors: Wang Zhong-Chun  ,   盐城师范学院物理系,盐城  224002
Published: December 2020

Starting from the classical equation of motion a dissipation transmission line,the mesoscopic dissipation transmission line is quantized.The quantum effects of the line under excited coherent states are investigated.The results indicate that the quantum fluctuations of the line are not only determined by the circuit parameter and the states of the circuit,but also dependent on the position of the line.
Comparative study on electronic structures of MgB2-like borides
Authors: Chai Yong-Quan  , Jin Chang-Qing  , Liu Bang-Gui  ,   (1)中国科学院物理研究所,北京  100080; (2)中国科学院物理研究所,北京  100080;廊坊师范学院物理系，廊坊  065000
Published: December 2020

The accurate first-principle method was used to calculate the electronic structures of eight MgB2 like borides at ambient and under high pressure co nditions. Their electronic structures were compared with each other. The results may be h elpful to modulate physical properties of the borides under high pressure.
Monter-Carlo simulation of surface magnetism of multilayered films
Authors: Feng Qian  , Huang Zhi-Gao  , Du You-Wei  ,   (1)福建师范大学物理系，福州  350007; (2)福建师范大学物理系，福州  350007;南京大学固体微结构物理国家重点实验室，南京  210093; (3)南京大学固体微结构物理国家重点实验室，南京  210093
Published: December 2020

Based on the Monte-Carlo simulation, the effects of both the ratio of surface interaction to bulk one Js/J and the multilayered thickness on the cri tical beh avior are studied. It is found that whether the phase transition temperature inc reases with increasing number of multilayers depends on the value of Js/J. Whe n the value of Js/J is above a certain critical value, the system bec omes orde red in the surface before it gets in order in the bulk. Below this critical valu e, one can find that a magnetically disordered surface can coexist with a magnet ically ordered bulk phase. For a small Js/J, the transition temperatu re increa ses slowly with the increase of Js/J and finally are equal to the transiti on temperature of the bulk. When Js/J is large enough, the transition temperat ure increases linearly with the increase of Js/J.The simulated result s are con sistent with those derived by the mean field theory with the transfer matrix met hod, and well explain the experimental facts.
Heat conduction investigations of the Si bridge in infrared emitter using micro- Raman scattering
Authors: Cai Wei-Ying  , Li Zhi-Feng  , Lu Wei  , Li Shou-Rong  , Liang Ping-Zhi  ,   中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083
Published: December 2020

Micro-Raman scattaring has been used to study the characteristics of heat conduction on heavy boron-doped Si bridge in an infrared emitter. Based on the proper spectral modeling and the temperature dependence of the position of the Raman peak, the bridge temperature rise due to the heating of high power laser is obtained. Using this method and in the way of point by point, the direct imaging of heat conduction as a distribution map of temperature rise has been also obtained. Compared with the simulated temperature distribution obtained by the finite element software, the experimental and theoretical results are in agreement with each other. While experiments have revealed the local fluctuations of heat conduction in detail, reflecting the nonuniformity of the actual device, and providing experimental bases for the micro-device optimization of the structure design and its fabrication.
Mei symmetry, Noether symmetry and Lie symmetry of Hamiltonian system
Authors: Luo Shao-Kai  ,   长沙大学数学力学与数学物理研究所，长沙  410003
Published: December 2020

The Mei symmetry, i.e. the form invariance, of a Hamiltonian system is studied. The definition and the determining equation of Mei symmetry in the Hamiltonian system are given. The relations among the Mei symmetry, the Noether symmetry and the Lie symmetry are studied, and the conserved quantities of Hamiltonian system are obtained. An example is given to illustrate the application of the result.
New multi-order exact solutions to a kind of nonlinear evolution equations
Authors: Fu Zun-Tao  , Liu Shi-Kuo  , Liu Shi-Da  ,   北京大学物理学院，北京  100871
Published: December 2020

Based on the Lamé equation and new Lamé functions, the perturbation method and Jacobi elliptic function expansion method are applied to get the multi-order ex act solutions of a kind of nonlinear evolution equations (such as mKdV equation, nonlinear Klein-Gordon equation Ⅱ etc.), where some more new multi-order exact solutions are found among different nonlinear evolution equations. These multi- order exact solutions correspond to different periodic solutions, which can dege nerate into different solitary wave solutions, such as band-soliton, bell-shaped solitary wave, etc.
The coherent rotation model in micro-rectangle magnetic film system
Authors: Peng Zi-Long  , Wang Wei-Ning  , Zhu Tao  , Han Xiu-Feng  , Zhan Wen-Shan  ,   State Key Laboratory of Magnetism, Institute of Physics & Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080, China
Published: December 2020

Based on the micro-rectangle magnetic film system, and the shape and the tilt of crystal easy axis introduced into the Stoner-Wohlfarth model, it was found that the expansion of astroid was caused by the size dwindlement of the sample, while the defects in shape and the tilt of crystal easy axis would both result in the formation of asymmetrical astroid.These results illuminated that, in micron order magnetic film systems such as magnetic random access memory, the shape and the tilt of crystal easy axis are important for determining the switch field of the film.
Application of Haar-Gaussian wavelet transform to edge-detection
Authors: Song Fei-Jun  , Zhao Wen-Jie  , S. Jutamulia  , Song Jian-Li  , Yao Si-Yi  , Wang Dong  ,   (1)Optical and Photonic Engineering Department,University of Northern California,Petaluma,CA 94954,USA; (2)北方交通大学计算机学院,北京  100044; (3)兰州交通大学数理与软件工程学院，兰州  730070; (4)中国科学院大恒集团有限公司，北京  100086
Published: December 2020

The Haar-Gaussian wavelet transform is applied to analyze the pattern edges in the frequency domain and to establish a physical model for the edge detection. The bandwidth-matching algorithm is proposed. A telecentric optics is used to achieve a high-precision edge detection results with large-depth of focus.
Formation of self-assembly and the mechanism of Si nanoquantum dots prepared by low pressure chemical vapor deposition
Authors: Peng Ying-Cai  , M. Ikeda  , S. Miyazaki  ,   (1)广岛大学电气工学系，大学院先端物质科学研究科，日本广岛; (2)河北大学电子信息工程学院，保定  071002;中国科学院半导体研究所半导体材料科学重点实验室，北京  100083
Published: December 2020

Si nanoquantum dots have been formed by self-assembled growth on the both Si—O—Si and Si—OH bonds terminated SiO2 surfaces using the low-pressur e chemical vapor deposition (LPCVD) and surface thermal decomposition of pure SiH4 gas. We have experimentally studied the variation of Si dot density with Si—OH bonds density, deposition temperature and SiH4 pressure, and analyzed qu alitatively the formation mechanism of the Si nanoquantum dots based on LPCVD surface thermal dynamics principle. The results are very important for the control of the density and size of Si nanoquantum dots, and have potential applications in the new quantum devices.
Ordered arrays and magnetic properties of cobalt nanoparticles
Authors: Yang Hai-Tao  , Shen Cheng-Min  , Du Shi-Xuan  , Su Yi-Kun  , Wang Yan-Guo  , Wang Yu-Ping  , Gao Hong-Jun  ,   (1)北京大学电子显微镜实验室，北京  100871; (2)中国科学院物理研究所电子显微镜实验室，北京  100080; (3)中国科学院物理研究所纳米物理与器件实验室，北京  100080
Published: December 2020

Monodisperse cobalt nanoparticles are produced by high-temperature thermal decomposition method. The influence of the size of nanoparticles, evaporation temperature, organic solvent, and concentration on the formation of the cobalt nanoparticles array is studied by transmission electron microscopy and ultraviolet absorption. Preliminary results of the cobalt nonoparticles magnetic properties are presented. These results lay a good foundation for the further study of the physical properties and the application in nanoscale devices of magnetic nanoparticles.
Polaron and admittance spectroscopy of yttrium-doped lead tungstate single cryst al
Authors: Shen Han  , Xu Hua  , Chen Min  , Li Jing-De  ,   (1)江西宜春学院物理系,宜春  336000; (2)中山大学物理系,广州  510275
Published: December 2020

Both DC and AC conductance of Y-doped PbWO4 single crystal have been studied over a temperature range from ambient temperature to 160 ℃. Results of DC conductivity indicate that the carriers in PbWO4 in such a temperature ra nge are polarons other than ions, for a transition of polarons from energy band conduction to hopping conduction which characterized by a minimum of conductivity has been observed. AC conductivity obtained from admittance analysis is almost 3-orders higher than that of DC analysis, it ought to be mainly ascribed to the effect of dielectric. If conductivity and dielectric constant of a given system change together with frequency, AC measurement can only yield a total admittance spectrum, but is unable to separate conductivity spectrum from dielectric spectrum.
Deposition of nanoporous silica thin films by sol-gel
Authors: He Zhi-Wei  , Zhen Cong-Mian  , Lan Wei  , Wang Yin-Yue  ,   兰州大学物理系，兰州  730000
Published: December 2020

Low dielectric constant thin film of nanoporous silica synthesized by sol-gel was deposited on Si(100) substrate by spin coating. By detecting —CH3 substituted for —OH species, which can avoid the destruction of network, surface modification was identified by Fourier transform infrared spectroscope. The hole size was about 70-80 nm observed from scanning electron microscope. By adjusting the pH value of the sol, we found that the gel time increased with the decrease o f the pH value of the sol. When heating the modified film at different temperatu res (60-400 ℃)， we can obtain the lowest dielectric constant 2.05 at 300 ℃ .
A molecular dynamics study of energetic particle bombardment on diamond
Authors: Li Rong-Bin  , Dai Yong-Bing  , Hu Xiao-Jun  , Shen He-Sheng  , He Xian-Chang  ,   上海交通大学金属基复合材料国家重点实验室，上海  200030
Published: December 2020

Molecular dynamic simulations, utilizing the Tersoff many-body potential, are used to investigate the microscopic processes of a single boron atom with an energy of 500 eV implanted into the diamond (001) 2×1 reconstructed surface. By calculating the variation of the mean coordination number with time，the lifetime of a thermal spike created by B bombardment is about 0.18ps. Formation of the split-interstitial composed of projectile and lattice atom(B—C) is observed. The total potential energy of the system decreases about 0.56 eV with a stable B split-interstitial existing in diamond. Lattice relaxations in the diamond (001) 2×1 reconstructed surface or near surface of the simulated have been discussed, and the results show that the outermost layer atoms tend to move inward and other atoms move outward, while the interplanar distance between the outermost layer and the second layer has been shortened by 15%,compared with it s starting interplanar distance. Stress distribution in the calculated diamond c onfiguration is inhomogeneous. After boron implanted into diamond with an energy of 500 eV, there is an excess of compressively stressed atoms in the lattice, w hich induces the total stress being compressive.
Density functional theory study on the electronic structure of UAl3 a nd USn3
Authors: Tan Ming-Qiu  , Tao Xiang-Ming  , Xu Xiao-Jun  , Cai Jian-Qiu  ,   浙江大学物理系，杭州  310027
Published: December 2020

We report an ab initio study on the electronic properties of 5f states in UX3( X=Al,Sn) by full-potential linear muffin tin orbitals L(S)DA calculations. The r elativistic effects which are quite remarkable for heavy atoms such as U, have b een treated by using scalar relativistic and spin-orbital coupling corrections. The calculations presented in this article have addressed following issues:first ly, the numerical results illustrates the different U 5f itineracy in UAl3 and USn3 qualitatively, and then the heavy fermion behavior of USn3 ;secondly, u sing Stuttgart-fatband analysis, we have confirmed the above conclusion quantita tively. In addition to the above results, the calculation involved in this resea rch has resolved the discrepancy between previous density functional theory stud ies on these compounds, especially the band structure dispersion in M-X directio n of simple cubic USn3. In conclusion, this study has approached a mo re precis e description for these uranium compounds on the basis of modern density functio nal theory calculation and described USn3 as a heavy fermion system d ue to its localized U 5f electronic states theoretically.
First-principles calculations on the geometry and the electronic structure of Pb Te(001) surface
Authors: Ma Jian-Xin  , Jia Yu  , Liang Er-Jun  , Wang Xiao-Chun  , Wang Fei  , Hu Xing  ,   郑州大学物理工程学院,郑州  450052
Published: December 2020

The geometry and electronic structure of PbTe(001) surface are calculated using the density functional theory method. It is shown that the (001) surface has no reconstruction and exhibits a significant oscillatory geometric relaxation. The top-to-second layer distance contracts by 4.5% and the second-to-third layer dis tance expands by near 2.0%. In addition, the surface shows a strong rumpling. Th e electronic structure of PbTe(001) surface differs from that of the bulk. With respect to the bulk energy gap at the L point, the surface energy gap broadens a t the X point. The surface states or resonance states are localized mainly near the top of the valence band and the bottom of the conduction band, while there a re no new surface states appearing in the fundamental energy gap. The density of state at Fermi level of the relaxed structure of PbTe(001) surface is very low, thus it is very stable.
The influence of Gd doping at A site on the magnetic and electrical properties i n La0.7Sr0.3MnO3
Authors: Liu Ning  , Gao Gui-Zhen  , Tong Wei  , Zhang Yu-Heng  ,   (1)宿州师范专科学校物理系,宿州  234000; (2)宿州师范专科学校物理系,宿州  234000;中国科学技术大学结构分析开放实验室,合肥  230026; (3)中国科学技术大学结构分析开放实验室,合肥  230026
Published: December 2020

The M-T curves， M-H curves, infrared spectra, Raman spectra，ρ-T curves and MR -T curves of La0.7-xGdxSr0.3MnO3 (x= 0.00, 0.10, 0.15, 0.20, 0.30 , 0.40, 0.50, 0.60, and 0.70) are studied. The experimental results indicate tha t with increasing Gd doping, the system undergoes a transition from long-range f erromagnetic order to the cluster-spin glass state and further to an antiferroma gnetic order. With heavily doping content, the transport property exhibits an ab normal behavior under magnetic background. The variation in magnetic structure a nd extra magnetic coupling caused by Gd doping lead to colossal magnetoresista nce.