bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of Local Lattice Distortion in Silicon by Imaging-Plate Plane-Wave X-Ray Topography with Image Magnification
Authors: Kawado Seiji , Kudo Yoshihiro , Kojima Shigeru , Liu Kuang Yu , Ishikawa Tetsuya
Published: October 2002

One-dimensional image magnification was applied to imaging-plate plane-wave X-ray topography using synchrotron radiation, in order to improve the spatial resolution in measurements of variations in local lattice distortion in silicon. The distortion analysis was performed using the intensity change of a rocking curve obtained through a 5× magnifier crystal when the sample crystal was rotated around the Bragg angle. This article describes the result of measurements of lattice distortion due to striations in the growth direction in as-grown Czochralski silicon crystals.
X-Ray Photoelectron Spectroscopy Studies of Titanium Nitride Barrier Metals Prepared by Low-Pressure Metalorganic Chemical Vapor Deposition
Authors: Chang Y. H. , Won S. J. , Oh J. E. , Paek S. H. , Lee H. D. , Choi J. S. , Lee S. I. , Ahn S. T. , Lee J. G.
Published: October 2002

Titanium nitride (TiN) films prepared by means of low-pressure metalorganic chemical vapor deposition (LP-MOCVD) with the tetrakis-dimethyl-amino titanium (TDMAT) and ammonia, attempting for producing conformal barrier metals for ultra-large scale integrated devices, are studied by means of X-ray photoelectron spectroscopy (XPS) in conjunction with Ar ion bombardment. In the detailed analysis of XPS spectra of the C 1 s region composed of two peaks corresponding to the chemical bondings of hydrocarbon and Ti-C, it is found that the relative intensity ratio between two peaks can be a direct measure of film properties, and that the chemical bonding of hydrocarbon dominates as the film thickness increases and the deposition temperature decreases.
Silicon Etching Employing Negative Ion in SF6 Plasma
Authors: Shindo Haruo , Sawa Yoshio , Horiike Yasuhiro
Published: October 2002

For a feasibility study of plasma etching employing bipolar ions, Si etching by negative ion was studied in SF6 plasma. Negative ions were confirmed by Langmuir probe measurements of ion currents, in which the current ratio of both polarity ions became about unity in a down-stream region at 90 mTorr pressure. In these down-stream region, Si etching was observed not only at negative DC bias but also at positive bias, indicating negative ion etching. The activation energy of etching by negative ion was found quite low compared with that by positive ion with the same bias energy. One possible explanation for this result is that the ion species are different for the polarity.
Electron-Stimulated Desorption and in situ Scanning Electron Microscopy Study on Self-Developing Reaction of High-Resolution Inorganic Electron Beam Resist
Authors: Watanabe Heiji , Fujita Jun-ichi , Ochiai Yukinori , Matsui Shinji , Masakazu Ichikawa Masakazu Ichikawa
Published: October 2002

Self-developing reaction of high-resolution inorganic electron beam resist based on AlF3-doped LiF (LiF(AlF3)) film is studied. Electron-stimulated desorption (ESD) from the inorganic resist is characterized by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It is found that a metal-rich layer formed by preferential fluorine desorption from the outermost surface due to ESD reaction suppresses the subsequent fluorine desorption. This indicates that surface diffusion of the residual metal plays an important role in the seff-developing reaction. A conventional scanning electron microscope (SEM) is also employed for fabrication of a nanometer-scale pattern on the film and its in situ surface observation. SEM images of the inorganic resist after the direct patterning and during electron beam irradiation suggest that metal diffusion occurs. This result correlates well with the reaction model obtained from desorption characteristics.
Spectrum Analysis of Recorded Magnetization Using Magnetic Force Microscopy
Authors: Honda Yukio , Inaba Nobuyuki , Tomiyama Futoshi , Yamamoto Tomoo , Masaaki Futamoto Masaaki Futamoto
Published: October 2002

Spectrum analyses of recorded magnetization were performed using magnetic force microscopic (MFM) images to quantitatively analyze the relationship between the magnetization structure and the reproduced signal output. Repeated one-dimensional Fourier analyses were performed on an MFM image along the recording direction of the disk medium for a certain width with a pitch of about 70 nm. The dependence of MFM signal intensity on wavelength was obtained through Fourier transformation. Differences in the noise characteristics of CoCrTa media with different Cr compositions were investigated. Several peaks in the Fourier-transformed spectrum are related to the magnetic cluster size and/or the magnetic cross-linking distance between neighboring recorded bits. The magnetic interactions were found to extend up to about 0.5 µ m and 1 µ m for magnetically recorded CoCr16Ta4 and CoCr10Ta4 media, respectively.
Distribution of Grown-in Crystal Defects in Silicon Crystals Formed by Point Defect Diffusion during Melt-Growth: Disappearance of the Oxidation Induced Stacking Faults-Ring
Authors: Tomiura Ryuichi Habu
Published: October 2002

A set of requirements for the diffusion coefficients and the equilibrium densities of self-interstitials and vacancies in a silicon crystal were derived from macroscopic experimental quantities. It was shown that the combination of the diffusion coefficients and the equilibrium densities which satisfy the derived requirements and the phenomenological diffusion equations proposed previously by the present authors can give the diffusion profiles of self interstitials and vacancies which agree well with the distribution of the grown-in crystal defects observed in a dislocation free, Czochralski (CZ)-silicon single crystal. The calculated results are able to explain the movement of the oxidation induced stacking faults (OSF)-ring depending upon crystal growth rate and formation of the radial distribution of the micro-defects in a CZ-wafer reported previously.
In0.52Al0.48As/InxGa1-xAs (0.53<x<1.0) Pseudomorphic High Electron Mobility Transistors with High Breakdown Voltages: Design and Performances
Authors: Dickmann Jürgen , Riepe Klaus , Geyer Arthur , Maile Bernd E. , Schurr Anton , Daembkes Michael Berg
Published: October 2002

The search for suitable ways to improve the high electron mobility transistors (HEMT's) device performances has stimulated the turbulent research work on pseudomorphic layer structures. Recent interest has been focused on pseudomorphic InAlAs/InGaAs HEMTs. In this paper we report on the design and fabrication of In0.52Al0.48As/In

x

Ga1-
x

As (0.53<x<1.0) pseudomorphic HEMTs. The main subject of the simulation and experimental work is the design of the channel to allow a maximum InAs molefraction while maintaining excellent device performance. The general results of our investigation are that the current handling capability and the high speed performance improves with x, while the breakdown voltage continuously degrades with increasing x. From our investigation an indium molefraction of x=0.7 was found to be optimum for the high speed performance.
Optical Cavity Based on Porous Silicon Superlattice Technology
Authors: Araki Minoru , Hideki Koyama Hideki Koyama , Nobuyoshi Koshida Nobuyoshi Koshida
Published: October 2002

It is demonstrated that luminescent porous silicon (PS) is applicable to a vertical optical cavity which operates at wavelengths in the visible region. The PS device consists of a high-reflectivity thin Ag film, a light-emitting PS layer, and a quarter-wavelength multilayer reflector fabricated by precisely controlled PS superlattice (PSSL) technology. The reflectivity of a prepared PSSL mirror is higher than 90% at designed wavelengths. When excited by a UV laser, the device acts as a Fabry-Perot resonator. Based on experimental studies of emission spectra as a function of major design parameters (the number of PSSL pairs and the cavity length), the linewidth is significantly decreased to 6 meV in full width at half-maximum. The change in the linewidth with the cavity length is consistent with the behavior expected from a simplified theoretical analysis. These results confirm that PS is applicable for silicon-based photonic devices.
Fabrication of a Si Nanometer Column PN Junction and Implanted Defect Evaluation by Transmission Electron Microscopy
Authors: Sukesako Hiroyasu , Kawasaki Takashi , Sakaue Hiroyuki , Shingubara Shoso , Horiike Takayuki Takahagi
Published: October 2002

We have proposed a Si nanometer column 1-D PN junction which allows electrons to tunnel between P- and N-regions across a depletion region. In order to observe the 1-D tunneling effect, heavy doping with both P- and N-type impurities is necessary. The present work investigated elimination of defects caused by ion implantation in the fine Si columns which were less than 50 nm in diameter by TEM. In the case of heavy doping with As or BF2 the as-doped structure is amorphous, and recrystallization is observed after annealing at temperatures above 600°C. Typical defects such as dislocations which are parallel to the {111} planes, twins which are formed on the {111} planes, and Si microcrystals which are differently oriented from the Si bulk of the substrate are observed in Si columns with diameters of larger than 20 nm. No defects are observed in ultrafine Si columns with diameters of less than 20 nm. It is suggested that defects formed during ion implantation diffuse to the surface or the Si/SiO2 interface of the ultrafine Si columns during annealing. The results indicate that it is possible to fabricate a 1-D PN junction with no defects.
Surface-Reaction-Controlled Tungsten CVD Technology for 0.1-µm Low-Resistive, Encroachment-Free CMOS-FET Applications
Authors: Nakamura Yoshitaka , Kobayashi Nobuyoshi , Hisamoto Digh , Umeda Kazunori , Ryo Nagai Ryo Nagai
Published: October 2002

A reliable and manufacturable tungsten (W) stacked source/drain (S/D)-and-gate technology has been developed which is applicable to conventional 0.1 µm complementary metal-oxide-semiconductor field-effect transistors (CMOS-FETs). A low-resistive (2–3 Ω/sq.) and encroachment-free S/D has been achieved. This technology has overcome two major problems in the selective chemical vapor deposition (CVD) of W. First, the difference in the thickness of W films grown on p+ and n+ silicon (Si) is reduced by Si-light-etching treatment. Second, encroachment during W-CVD is suppressed by a tungsten hexafluoride (WF6) high-pressure process. Excellent electrical characteristics have been obtained in 0.1 µm CMOS-FETs using the W stacked S/D-and-gate technology.
W as a Bit Line Interconnection in Capacitor-Over-Bit-line (COB) Structured Dynamic Random Access Memory (DRAM) and Feasible Diffusion Barrier Layer
Authors: Byun Jeong Soo , Kim Jun Ki , Jin Won Park Jin Won Park , Jae Jeong Kim Jae Jeong Kim
Published: October 2002

In this paper, we discuss the formation of a TiN/TiSi2 bilayer from TiN
X
and its utilization as a diffusion barrier for the W bit-line process in COB structured DRAM devices. Since the TiSi2 layer formed on a Si substrate is very thin and uniform, the TiN
X
-contacted n- and n+ junction showed desirable electrical properties. The compact structure of the overlying TiN due to its lack of grain boundary voiding enabled the TiN
X
to be used as a diffusion barrier for the W bit line process.
Low Damage In Situ Contact Cleaning Method by a Highly Dense and Directional ECR Plasma
Authors: Park In Seon , Yoon Meeyoung , Lee Hyeon Deok , Park Chang Soo , Wee Young Jin , Choi Gil Heyun , Oh Kwan Young , Sang In Lee Sang In Lee , Moon Yong Lee Moon Yong Lee
Published: October 2002

In situ electron cyclotron resonance (ECR) plasma cleaning process is applied for the cleaning of sub-half-micron-sized contacts in dynamic random access memory (DRAM) devices. ECR plasma cleaning shows superior performance over reactive ion etch (RIE), RF plasma, and dilute HF wet cleaning methods. The high density but low incident energy of the ECR plasma process minimizes surface damage. In addition, the high directionality of this process effectively removes surface impurities from sub-half-micron-sized contacts, resulting in low and stable contact resistance. The ECR plasma cleaning process also reshapes the contact profile in favor of contact filling by Al reflow and is extremely effective for contact cleaning, especially when H2 is incorporated to the ECR plasma cleaning process. Thus it shows great promise as a future contact cleaning technology of choice.
An Efficient Improvement for Barrier Effect of W-filled Contact
Authors: Yeh Wen-Kuan , Chan Kuang-Yang , Chang Ting-Chang , Tsai Ming-Hsing , Chen Sheng-Hsiung , Lin Mao-Chieh Chen
Published: October 2002

A post chemical vapor deposition of tungsten (CVD-W) treatment by N2 plasma is proposed to suppress the WAl12 formation during subsequent thermal annealing, which improves the thermal stability of W-filled contact. Selective CVD-W is employed to fill the contact hole. Following W deposition, in situ N2 plasma treatment is performed prior to Al alloy metallization. It is shown that this post CVD-W treatment efficiently suppresses the formation of WAl12, resulting in an improvement of the barrier capability of W-filled contact.
Single Electron Device with Asymmetric Tunnel Barriers
Authors: Matsumoto Yoshinari , Hanajiri Tatsuro , Toyabe Tohru , Sugano Takuo
Published: October 2002

A single electron device with asymmetric tunnel barriers (ATBs) is proposed, and its operation simulated by computer. Current in the ATB structure is dominated by Fowler-Nordheim tunneling while that in a conventional symmetric tunnel barrier (STB) structure is determined by direct tunneling. Consequently, the ATB has two remarkable advantages over STB. First, the tunnel resistance of ATB depends on the energy of tunneling electron and is determined independently of the barrier capacitance. Second, the tunneling of electrons becomes almost unilateral in ATB and bilateral in STB. These advantages of ATB make it easier to fabricate single electron circuits with high speed, high temperature and low power consumption.
Nanometer-Scale Current-Voltage Spectra Measurement of Resonant Tunneling Diodes Using Scanning Force Microscopy
Authors: Tanimoto Masafumi , Kanisawa Kiyoshi , Masanori Shinohara Masanori Shinohara
Published: October 2002

We demonstrate that a novel method of current-voltage (I-V) spectra measurement by scanning force microscopy (SFM) reveals local electrical characteristics of resonant tunneling diodes (RTDs) on a nanometer scale. Measured SFM I-V spectra of RTDs show negative differential resistance features, and the spatial resolution of this method was found to be 20 nm. Experimental evidence for the quantized nature of an SFM pointcontact was observed for the first time. High spatial resolution of this method was confirmed by a simple calculation for the area of current flow through RTD. Fine structure in the SFM I-V spectra was also observed.
InP-Based High-Performance Monostable-Bistable Transition Logic Element (MOBILE): an Intelligent Logic Gate Featuring Weighted-Sum Threshold Operations
Authors: Chen Kevin J. , Koichi Maezawa Koichi Maezawa , Masafumi Yamamoto Masafumi Yamamoto
Published: October 2002

The first InP-based monostable-bistable transition logic elements (MOBILEs), which have the advantages of multiple-input and multiple-functions, are demonstrated based on the monolithic integration of resonant-tunneling diodes and high electron mobility transistors. High peak current density, high peak-to-valley ratio, and high transconductance, which are required for high-performance MOBILEs, are demonstrated in the InP-based material system. A fabricated MOBILE, which has three-input gates with a 1:2:4 width ratio can perform weighted-sum threshold logic operation. The weighted-sum threshold logic opeation has a wide range of applications in new computing architectures such as neural networks and cellular automata.
Spectral Shape Analysis of Photoluminescence Excitation in Semiconductors
Authors: Masatoshi Warashina Masatoshi Warashina , Michio Tajima Michio Tajima
Published: October 2002

Spectral shapes of photoluminescence (PL) excitation in semiconductor crystals are analyzed on the basis of the carrier continuity equation in the steady state. The measured PLE (Photoluminescence Excitation) spectral curves are found to be in reasonable agreement with the theoretically calculated spectrum. The PL intensity increases with an onset of the band-gap energy of the sample. The PL intensity of a thick sample increases with increasing excitation photon energy and then decreases after reaching a maximum. The spectral intensity reduction in the high-energy region is due to the increase in surface recombination. The PL intensity of a thin sample increases in proportion to the absorption coefficient, where the diffusion length of the minority carriers is sufficiently larger than the sample thickness.
Optical Characterization of InAs Quantum Dots Fabricated by Molecular Beam Epitaxy
Authors: Saitoh Toshiya , Takeuchi Hayato , Jun Konda Jun Konda , Kanji Yoh Kanji Yoh
Published: October 2002

Optical characterization were performed on patterned InAs dots based on InAs/InAlAs hetero-structure and the self-assembled InAs dots grown on GaAs. Unexpectedly high peak energy shift in photoluminescence (PL) and cathodoluminescence (CL) was observed from InAs dots based on InAs/InAlAs heterostructure. PL results of self assembled InAs dots grown on GaAs also showed unexpectedly high peak energy. CL spectra from each single InAs dot suggested luminescence from highly strained dots contribute to shift the average luminescence peak towards higher energy. The high PL peak energy from the self-assembled InAs dots turned out to be composed of strain-induced band-gap widening (28%), carrier confinement effect (17%) in addition to unstrained band-gap energy (29%). 26% of the total PL peak energy remained unassigned.
0.86 eV Platinum Schottky Barrier on Indium Phosphide by In Situ Electrochemical Process and Its Application to MESFETs
Authors: Uno Shouichi , Hashizume Tamotsu , Kasai Seiya , Nan-Jian Wu Nan-Jian Wu , Hideki Hasegawa Hideki Hasegawa
Published: October 2002

Pt Schottky barrier diodes (SBDs) with a high Schottky barrier height of 0.86 eV and an ideality factor of near unity were successfully realized by a novel in situ electrochemical process. Applying this novel technique to InP metal semiconductor field effect transistors (MESFETs), good gate control of drain current with pinch-off, an effective channel mobility of 1,840 cm2V-1s-1 and no drain current drift behavior were achieved. The InP MESFET operates even under a positive gate bias, showing feasibility of enhancement-mode operation as well as depletion-mode operation.
Characterization of In0.46Ga0.54P/n +-GaAs Heterostructures By Photoellipsometry
Authors: Saitoh Tadashi , Watanabe Kenichi , Hyuga Fumiaki , Yi-Ming Xiong Yi-Ming Xiong
Published: October 2002

Photoellipsometry, a contactless optical method, was used for the characterization of In0.46Ga0.54P/
n

+-GaAs heterostructures exposed to room air. Two samples were studied, each containing an undoped In0.46Ga0.54P layer of thickness L (L=40 and 100 nm) grown on top of a heavily doped (100) GaAs substrate by metal-organic chemical vapor deposition. The measured spectra were analyzed using the Franz-Keldysh theory, with inclusion of broadening effects. The results of our specral analysis indicate that, for each sample investigated, there existed an almost uniform built-in electric field in the top layer. Using the built-in field strength obtained from the spectral analysis and the In0.46Ga0.54P layer thickness, we found that the surface Fermi level for each sample was pinned near mid-band-gap energy of In0.46Ga0.54P, with a value of 0.94–0.95 eV.
Scanning Tunneling Microscope Study of (001)InP Surface Prepared by Gas Source Molecular Beam Epitaxy
Authors: Yang Bing Xiong , Ishikawa Yasuhiko , Tsuyoshi Ozeki Tsuyoshi Ozeki , Hideki Hasegawa Hideki Hasegawa
Published: October 2002

(001)InP surface prepared by gas source molecular beam epitaxy (GSMBE) using tertiarybutylphosphine (TBP) as P source was studied by ultrahigh-vacuum scanning tunneling microscope (UHV-STM), reflection high-energy electron diffraction (RHEED) and X-ray photoelectron spectroscopy (XPS). It was found that the P-stabilized (2×4) reconstructed (001)InP surfaces can be obtained by annealing the (2×1) reconstructed surface which contains excess phosphorus. (2×4) reconstructed surfaces were found to possess the missing-dimer arrangements with at least two microscopic structures, α phase with two missing-dimer rows and β phase with one missing-dimer row, depending on the annealing temperature of the (2×1) surface. The (2×4)α phase is more stable with a wider range of annealing temperature, whereas the (2×4)β phase was obtained by annealing only near 330°C. The (2×4)α phase was observed even on a partially oxidized surface having many oxide patches, showing its remarkable stability.
Proposal of a Technique to Detect Subsurface Hot Electrons with a Scanning Probe Microscope
Authors: Francisco Vazquez Francisco Vazquez , Kazuhito Furuya Kazuhito Furuya , Daisuke Kobayashi Daisuke Kobayashi
Published: October 2002

In this paper we introduce a new experimental technique called scanning hot electron microscopy (SHEM), which allows detection of hot electrons emitted from sub-surface semiconductor structures. The principle of operation is basically the same as that of a reverse biased ballistic-electron-emitting microscope (BEEM), but with several additional modifications necessary to ensure that the current of hot electrons flowing from the sample to the probe exceeds that of thermalized electrons. In particular, hot electrons are required to surmount the gap barrier rather than tunnel through it. The possibility of SHEM operation is theoretically demonstrated for several material combinations of the probe and the sample, and a suitable experimental setup is proposed. Once this technique is fully implemented, it will allow for the study of electron wave phenomena in subsurface semiconductor structures.
Photoluminescence and Cathodoluminescence Investigation of Optical Properties of InP-Based InGaAs Ridge Quantum Wires Formed by Selective Molecular Beam Epitaxy
Authors: Hajime Fujikura Hajime Fujikura , Hideki Hasegawa Hideki Hasegawa
Published: October 2002

Optical properties of InP-based InGaAs ridge quantum wires formed by selective molecular beam epitaxy (MBE) growth were characterized in detail by using cathodoluminescence (CL) and photoluminescence (PL). Both the CL and PL spectra had strong emission peaks with narrow widths. Spot-excited CL images confirmed that these peaks originated from ridge quantum wires. Depending on the excitation power, emission peaks showed energy shift and half-width change due to band filling. Temperature dependence of the PL emission peak followed that of the energy gap. The PL intensity decreased with increasing temperature, but was still fairly intense at room temperature. The behavior of PL intensity change with temperature was found to be the same for wires and reference wells, indicating the presence of a common nonradiative recombination mechanism.
Fabrication and Photoluminescence Studies of GaInAsP/InP 2-Dimensional Photonic Crystals
Authors: Toshihiko Baba Toshihiko Baba , Tomomi Matsuzaki Tomomi Matsuzaki
Published: October 2002

We have fabricated GaInAsP/InP compressive strained quantum-well two-dimensional (2D) photonic crystals, which are expected to exhibit an effective spontaneous emission control without discrimination by surface recombination. Electron beam lithography and methane-based reactive ion beam etching techniques were used to form submicron periodic structures. The photoluminescence from the formed structures was almost as strong as that from an as-grown wafer. In addition, it was observed that the emission inside the substrate plane was transverse-magnetic-polarized when the designed photonic bandgap for transverse-electric (TE) polarization overlapped with the emission frequency, while the emission from the as-grown wafer was TE-polarized. These results support the theory of spontaneous emission control effect by quantum confinement of photons and electrons.
Regular Array Formation of Self-Assembled InAs Dots Grown on Patterned (111)B GaAs Substrate by MBE
Authors: Saitoh Toshiya , Arata Tanimura Arata Tanimura , Kanji Yoh Kanji Yoh
Published: October 2002

We report, for the first time, self-assembled molecular beam epitaxial (MBE) growth of InAs dots on patterned (111)B GaAs substrates by Stranski-Krastanow growth mode. (111)B GaAs substrates were patterned by using conventional optical lithography process and wet-chemical etching. Self-assembled InAs dot growth was performed on both tetrahedral etch-pit pattern and trapezoidal grooves. InAs dots were found to be selectively grown on the bottom of the tetrahedral etch-pit with appropriate growth conditions. As for the growth on trapezoidal grooves, InAs dots were found to be periodically arrayed on the middle of one side of the slope of grooves patterned along [2*BAR*1*BAR**BAR*1*BAR*] direction and on the top and the bottom surface of grooves patterned along [0*BAR*1*BAR*1] direction. The observed periodic distributions of InAs dots on the patterned substrates are presumably caused by the periodic lattice strain distributions on the patterned surface at the initial stage of highly strained layer growth.
Biaxial Strain Effect on Wurtzite GaN/AlGaN Quantum Well Lasers
Authors: Masakatsu Suzuki Masakatsu Suzuki , Takeshi Uenoyama Takeshi Uenoyama
Published: October 2002

Subband structures and optical gains of both unstrained and biaxial strained wurtzite GaN/AlGaN quantum well (QW) laser diodes (LDs) are theoretically investigated by the 8×8 k\cdotpp theory, with the assistance of the first-principles calculations in the derivation of the required parameters such as deformation potentials. The strong electron affinity and the small spin-orbit coupling of a nitrogen yield much heavier effective masses even in the QWs. It plays an essential role in causing a higher threshold current density for any well length than GaAs/AlGaAs QW LDs. Considering a biaxial strain induced by the lattice mismatch, the optical gain property qualitatively improves for any well length. However, the effect on the reduction of the threshold current density is quantitatively not so effective as GaAs/AlGaAs QW LDs.
Schottky Barrier Height Reduction for p-ZnSe Contacts by Sulfur Treatment
Authors: Onomura Masaaki , Saito Shinji , Rennie John , Nishikawa Yukie , Parbrook Peter J. , Masayuki Ishikawa Masayuki Ishikawa , Gen-ichi Hatakoshi Gen-ichi Hatakoshi
Published: October 2002

We have demonstrated the relationship between the structural and electrical properties of the chemically treated p-type ZnSe surface. The unstable Se-rich ZnSe surface, formed by an acid etchant, is shown to be removed by sulfur treatment. The sulfur treatment has been found to have the effect of lowering the Schottky barrier height at the Au/p-type ZnSe interface. This barrier lowering has been found to be effective in reducing the operation voltage of the ZnSe-based devices.
Dependence of CdZnSe/ZnMgSSe Laser Diode Operating Characteristics on Band Gap and Net Acceptor Concentration of p-Type Cladding Layer
Authors: Nakatsuka Shin'ichi , Gotoh Jun , Mochizuki Kazuhiro , Taike Akira , Masahiko Kawata Masahiko Kawata , Masayuki Momose Masayuki Momose
Published: October 2002

The dependence of CdZnSe/ZnMgSSe laser diode characteristics on the band gap and net acceptor concentration of the cladding layer is investigated theoretically to provide quantitative guidelines for cladding layer design. Carrier overflow from the active layer to the cladding layer and the recombination current at the active layer are calculated taking into consideration band bending around the active layer. The calculated results are consistent with experimental and reported characteristics. The improvement in laser diode characteristics due to the use of the superlattice cladding layer and ZnSe substrate is estimated by this calculation. The improvement due to the use of the ZnSe substrate is more effective when the cladding layer band gap is less than 2.95 eV, and the superlattice is more effective when the band gap is more than 2.95 eV. It is shown that operating voltage of less than 5 V can be achieved for a 490 nm laser diode when using a superlattice cladding layer.
Metalorganic MBE Growth of Nitrogen-doped ZnSe: TAN Doping and Nitrogen Plasma Doping
Authors: Go Sato Go Sato , Takahiro Numai Takahiro Numai , Mitsuo Hoshiyama Mitsuo Hoshiyama , Ikuo Suemune Ikuo Suemune , Hideaki Machida Hideaki Machida , Norio Shimoyama Norio Shimoyama
Published: October 2002

Growth of ZnSe and nitrogen doping were carried out by metalorganic molecular beam epitaxy (MOMBE). In this study metalorganic precursors were introduced into the growth chamber directly without precracking. We studied two nitrogen doping techniques. First, doping with the nitrogen precursor triallylamine (TAN) was studied. It was found that TAN decomposes above 300°C by quadrupole mass spectrometry. The doping properties of TAN were critically dependent on the VI/II ratio during growth. However contrary to our expectation, the doped ZnSe films tended to be n-type. The other nitrogen-doping technique involves doping with nitrogen gas activated by an electron cyclotron resonance plasma. In the samples doped with the nitrogen plasma, donor-acceptor pair emission was dominant. The net acceptor concentration up to 2.3×1017 cm-3 was measured in samples grown using this doping technique.
X-Ray Investigations and Determination of the Dielectric Properties of the Compound Ba4.5Gd9Ti18O54
Authors: Matjaž Valant Matjaž Valant , Danilo Suvorov Danilo Suvorov , Drago Kolar Drago Kolar
Published: October 2002

The composition of the Gd variant of the Ba6-
x

R8+2/3
x

Ti18O54 family of solid solutions ( R=rare earth) was determined by investigating its high temperature phase relations and by wavelength-dispersion spectroscopic analysis. The composition of the compound was determined to be Ba4.5Gd9Ti18O54, which corresponds to x=1.5 without a detectable solid solubility range. The intensities of the diffraction lines are not in accordance with published values in the powder diffraction file (No. 43–233). An investigation of the thermal stability revealed that Ba4.5Gd9Ti18O54 starts to decompose at a temperature around 1350° C. It decomposes into a Gd2Ti2O7, BaTi2O5 solid solution with Gd2O3, and probably Ba4Ti13O30. However, during slowly cooling metastable BaTi2O5(ss) also decomposes into Ba6Ti17O40 and BaTiO3 solid solution with Gd2O3. Single phase Ba4.5Gd9Ti18O54 ceramics displayed a dielectric constant (ε
r) of 76.1, a Q
x
f-value of 2050 and a temperature coefficient of the resonant frequency (τ f) of -35 ppm/K.
Theoretical Analysis of Oxygen-Excess Defects in SiO2 Thin Film by Molecular Orbital Method
Authors: Takeshi Kanashima Takeshi Kanashima , Masanori Okuyama Masanori Okuyama , Yoshihiro Hamakawa Yoshihiro Hamakawa
Published: October 2002

Energy states of oxygen-excess defects in SiO2 have been studied by theoretical analyses using molecular orbital calculation and discussed on the basis of comparison with photoluminescence of SiO2 thin films. Theoretical analyses have been carried out using both the semi-empirical and ab-initio methods, and have shown that the transition energy from the excited singlet state to the ground state is 2.32 eV with the STO-3G basis set and 2.40 eV with the 3-21G basis set, which are very close to the 2.4 eV photoluminescence peak measured in the photo induced chemical vapor deposition SiO2 thin film. This analysis and the effects of annealing in O2 and N2 atmospheres suggest that origin of the photoluminescence peak at 2.4 eV is oxygen-excess defect.
Low-Temperature CVD of Silicon Dioxide by Alkoxyl-Silane-Isocyanate
Authors: Uchida Yasutaka , Matsumura Shu Takei
Published: October 2002

We propose alkoxyl-silane-isocyanate [(RO)
n
Si(NCO)4-n
] as a new silicon source material for low-temperature chemical-vapor deposition of silicon dioxide. Detailed deposition characteristics and properties of the deposited film evaluated by auger electron spectroscopy (AES), X-ray photoemission spectroscopy (XPS) and Fourier transform IR (FTIR) are presented for ethoxyl-silane-isocyanate (R=C2H5). The deposition rate took a maximum value of 20 nm/h around 120°C and then decreased gradually with increasing deposition temperature T. The atomic ratio O/Si evaluated by AES was constant and about 2 for T≧200°C. The breakdown-field strength and low-field resistivity were 3.2 MV/cm and 1.3×1015 Ωcm, respectively.
Preparation of Low-Dielectric-Constant F-Doped SiO2 Films by Plasma-Enhanced Chemical Vapor Deposition
Authors: Lim Sang Woo , Shimogaki Yukihiro , Nakano Yoshiaki , Tada Kunio , Hiroshi Komiyama Hiroshi Komiyama
Published: October 2002

The delay due to the dielectric constant of an interlayer film results in the limited performance of very large-scale integrated circuits (VLSI). One solution to this problem is the use of a low-dielectric-constant interlayer film such as F-doped SiO2. We were able to obtain F-doped SiO2 films with dielectric constants as low as 2.3 and good step coverage by adding CF4 to SiH4/N2O plasma-enhanced chemical vapor deposition (PECVD). Our study focuses on the mechanism of the decrease in the dielectric constant and that of process improvement. It appears that a decrease in the dielectric constant is due to the decrease in the ionic polarization. The change in the Si–O stretching mode due to CF4 addition seems to be the most important factor in the decrease in the dielectric constant. The improvement of the step coverage and the decrease in the film growth rate are due to the decrease in the sticking probability of the film-forming species.
High-Rate Bias Sputtering Filling of SiO2 Film Employing Both Continuous Wave and Time-Modulated Inductively Coupled Plasmas
Authors: Kobayashi Yasuo , Chinzei Yasuhiko , Asanome Hiroshi , Kurosaki Ryo , Kikuchi Jun , Shingubara Shoso , Yasuhiro Horiike Yasuhiro Horiike
Published: October 2002

The SiO2 film deposition employing inductively coupled plasma (ICP) with SiCl2H2/O2 occurred rapidly in the low-density plasma region due to production of precursors of SiCl2H2O
x
(x=1–4). In an ICP CVD apparatus made with optimized distances between the antenna and the stage, and between the SiCl2H2 gas ring and the stage, a SiO2 film was with high deposition rate of more than 1 µm/min, 1.5 times the BHF etch rate of thermal oxide, and low Cl inclusion at a pressure of around 0.1 Torr. To supply ions to the Si wafer located in the ion-deficient plasma region, another time-modulated ICP antenna was set near the stage. Since deposition rate decreased with increasing wafer temperature, the laser the interference measurement of a Si wafer set on an RF-biased stage revealed the importance of the tight adhesion of the wafer to the stage. Ar+ ion bombardment during discharge on and off-time of 5 µs enabled us to fill Si trenches with SiO2 at a V
dc of 500 V.
Time-Dependent Dielectric Degradation (TDDD) Influenced by Ultrathin Film Oxidation Process
Authors: Mikihiro Kimura Mikihiro Kimura , Tadahiro Ohmi Tadahiro Ohmi
Published: October 2002

A complete hole-induced breakdown model suggests that the intrinsic oxide breakdown under an optimal low-field operation lifetime is not a critical limitation in thin oxide films (30–180 Å). Also, buildup of the oxide trapped charges and generation of the Si/SiO2 interface states during electrical stress, which is closely related to water-related bond breaking inside/at the interface of the amorphous thin oxide networks, decreases in a thin oxide film (∼50 Å). On the other hand, electrical stress-induced leakage current (SILC) through the oxides is markedly increased in the oxide film of around 50 Å thickness; also, the SILC is apparently dependent on the ultrathin film oxidation process. The origin of SILC can be modeled by the Si–O weak/strained bonds inside the amorphous thin oxide films in contrast to the water-related bond-breaking model. Thus the SILC phenomenon is a very important problem in the ultrathin oxide film reliability. Due to the need for a new measure of wafer level reliability to SILC, a time-dependent dielectric degradation (TDDD) method was developed for the evaluation of ultrathin oxide film reliability.
Ferroelectric Properties of BaMgF4 Films Grown on Si(100), (111), and Pt(111)/SiO2/Si(100) Structures
Authors: Aizawa Koji , Ichiki Tatsuya , Okamoto Tomoyuki , Eisuke Tokumitsu Eisuke Tokumitsu , Hiroshi Ishiwara Hiroshi Ishiwara
Published: October 2002

Ferroelectric properties of BaMgF4 (BMF) films grown on Si(100), (111) and Pt(111)/SiO2/Si(100) structures were studied. No ferroelectric polarization along the surface normal was observed for (011)-oriented BMF films grown on Si(100) substrates, while (120)-oriented BMF films grown on Si(111) and Pt(111)/SiO2/Si(100) structures clearly showed hysteresis characteristics with ferroelectric polarization. The remanent polarization values of the BMF films on Si(111) and Pt(111)/SiO2/Si(100) structures were 0.89 µC/cm2 and 5.0 µC/cm2, respectively. Fabrication and characterization of metal-ferroelectric-semiconductor (MFS) field effect transistors (FETs) using Si(111) substrates were attempted. It was observed that the threshold voltage of the fabricated MFS FETs was shifted upon applying a gate voltage.
Correlating Charge-to-Breakdown with Constant-Current Injection to Gate Oxide Lifetime under Constant-Voltage Stress
Authors: Uraoka Koji Eriguchi
Published: October 2002

In this paper we describe the Cumulative Damage Law which clarifies the relationship between the charge-to-breakdown with constant-current injection (Q
bd) and the time-to-breakdown with constant-voltage stress (t
bd). The oxide lifetime (t
bd) can be predicted from Q
bd by evaluating the time dependence of the gate current density J(t) under constant-voltage stress. The applicability of this relationship is verified for oxide thickness greater than 6 nm and various substrate temperatures in the range from 35°C to 150°C. It is found that the temperature dependence of the gate current density is responsible for the difference in the temperature-accelerating factors obtained using Q
bd and t
bd measurement methods, respectively.
Kinetics of Interface State Generation Induced by Hot Carriers in N-Channel Polycrystalline Silicon Thin-Film Transistors
Authors: Fortunato Guglielmo , Pecora Alessandro , Policicchio Irma , Plais Francois , Pribat Didier
Published: October 2002

Interface state creation, induced by hot hole injection, has been frequently observed in n-channel polysilicon thin-film transistors, when subjected to prolonged bias stress with negative gate biases. In this work we propose a new model for the kinetics of interface state formation, that closely links the interface state generation to the measured gate leakage current. The interface state generation mechanism appears to be driven by the recombination of hot holes (injected from the semiconductor active layer) with electrons (injected from the gate electrode). This model is shown to fit very well the time evolution of the interface states, as determined by the sheet conductance of the damaged region close to the drain.
Growth of [111]-Oriented Lead Zirconate Titanate Thin Film with Smooth Surface to Improve Electrical Properties
Authors: Satoshi Yamauchi Satoshi Yamauchi , Masaki Yoshimaru Masaki Yoshimaru
Published: October 2002

[111]-Oriented lead zirconate titanate (PZT) films with smooth surfaces were successfully grown on (111)-oriented polycrystalline Pt substrates after in-situ Ar-plasma cleaning by low-temperature reactive sputtering and rapid thermal annealing. The Pb composition was stoichiometrically controlled not only for total composition but also in the depth direction by low-temperature reactive sputtering. A (111)-oriented perovskite-phase PZT film with a very smooth surface was then obtained by rapid thermal annealing. The leakage current of quasi-epitaxial PZT films was markedly reduced to 10-7 A/cm2 and the equivalent SiO2 layer thickness of around 0.4 nm was obtained for the fatigue-free PZT films thinner than 100 nm.
Bismuth Titanate Thin Films on Si with Buffer Layers Prepared by Laser Ablation and Their Electrical Properties
Authors: Wenbiao Wu Wenbiao Wu , Keigo Fumoto Keigo Fumoto , Yoshihiro Oishi Yoshihiro Oishi , Masanori Okuyama Masanori Okuyama , Yoshihiro Hamakawa Yoshihiro Hamakawa
Published: October 2002

Bismuth titanate thin films are grown on SiO2 /Si and Pt substrates at temperatures of 300–500°C by the laser ablation method, and their structural and electrical properties investigated. The films prepared on Si substrates with a Pt or Bi2Ti2O7(BTO) buffer layer have c-axis and (117) orientations, although the films on Pt and SiO2/Si substrates orient preferentially along the c-axis and (117) direction, respectively. Capacitance-voltage hysteresis loops of bismuth titanate thin films on SiO2/Si and BTO/Si are observed corresponding to ferroelectric hysteresis of the film. Current-voltage characteristics of bismuth titanate films on Pt and BTO/Si substrates show low leakage current.
Memory Retention and Switching Speed of Ferroelectric Field Effect in (Pb, La)(Ti, Zr)O3/La2CuO4:Sr Heterostructure
Authors: Watanabe Yukio , Mitsuru Tanamura Mitsuru Tanamura , Yasuaki Matsumoto Yasuaki Matsumoto
Published: October 2002

We report long period memory retention characteristics and switching speed of (Pb, La)(Ti, Zr)O3/La2CuO4 field effect devices previously proposed by one of the authors. Most of the devices retained one-half of their initial conductance modulations induced by the ferroelectric field effect for about two weeks. Some retained memory for over 10 months, which markedly surpasses previously reported performances for the memory retention of ferroelectric field effect devices. The switching time of devices having effectively a 200-µm-long and 40-µm-wide gate area reduced to 10 µs, as the conductance between the source and drain increased. Such a short switching time is favorable for interpretation of the conductance modulation based on the field effect. Approaches to high density integration are discussed.
Behavior of Alkoxy-Functional Groups on Atmospheric-Pressure Chemical Vapor Deposition Using Alkoxysilane and Ozone
Authors: Koichi Ikeda Koichi Ikeda , Masahiko Maeda Masahiko Maeda
Published: October 2002

Behavior of alkoxy-functional [RO-] groups in an atmospheric-pressure chemical vapor deposition (APCVD) reaction using alkoxysilane and ozone is evaluated by alcohol addition. The RO- groups from the alcohol affect the flow characteristics of the APCVD reaction. Formation of a flowing-like profile can be accelerated by increasing the partial pressure of RO- groups in the reaction system when the added RO- groups are of the same size as, or smaller than, the RO- groups of silicon sources. When acceleration occurs, the amount of carbon and hydrogen atoms from RO- groups of added alcohols incorporated in the deposited film increases. Thermal desorption spectroscopy (TDS) shows three states for the carbon incorporated in the deposited film. Water desorption, which is related to the incorporated hydrogen, is also measured. Hydrolysis occurs at the residual terminal groups (i.e., Si–H and Si–OH), which are associated with the flow characteristics.
Elimination of Al Line and Via Resistance Degradation under HTS Test in Application of F-Doped Oxide as Intermetal Dielectric
Authors: Hwang Byung Keun , Choi Ji Hyun , Lee Soowong , Fujihara Kazuyuki , Chung U-In , Sang-In Lee Sang-In Lee , Moon-Yong Lee Moon-Yong Lee
Published: October 2002

Fluorine-doped silicon oxide (SiOF) as intermetal dielectric (IMD) layer was deposited by conventional plasma-enhanced chemical vapor deposition (CVD). The main issues in the application of SiOF as IMD are as follows: (1) instability of film properties such as stress and refractive index during HTS test, (2) desorption of H2O and HF gases from SiOF film, (3) increase of line resistance, (4) wedgelike defects of metal lines, and (5) via resistance degradation during HTS test at 350°C. The above problems in use of SiOF as IMD can be eliminated by the passivation of IMD with PE-SiN and the application of Ti underlayer before the second metal deposition.
Compositional Relation of GaAsxSb1-x and Related Compounds in Metalorganic Chemical Vapor Deposition Using tBAs and TMSb as Group V Precursors
Authors: Naozo Watanabe Naozo Watanabe , Yasuo Iwamura Yasuo Iwamura
Published: October 2002

Antimony rich solid composition in metalorganic chemical vapor deposition (MOCVD) of GaAs

x

Sb1-
x

, x<P
tBAs
0/(P
tBAs
0+P
TMSb
0), is generally observed in MOCVD growth in a lower-temperature range, 400 to low 500° C, in contrast to the arsenic rich solid compositional relation usually observed in growth in the higher-temperature range. A similar relation in InAs

x

Sb1-
x

is also observed. A growth model for this low-temperature range is proposed, where undecomposed or partially decomposed TMSb plays an essential role in the growth. Un-(or partially) decomposed TMSb has been assumed to remain at a higher concentration on the reaction surface than that evaluated applying a thermal equilibrium relation with Sb4 and to have a high reaction equilibrium coefficient with Ga and to leave methyl groups on some surface Sb's thereby partly suppressing Ga surface reaction. Our calculated result explains essential features of the compositional relation.
A Modified Harmonic Oscillator Approximation Scheme for the Dielectric Constants of GaAs, InP and GaP
Authors: Guolin Yu Guolin Yu , Tetsuo Soga Tetsuo Soga , Takashi Jimbo Takashi Jimbo , Masayoshi Umeno Masayoshi Umeno
Published: October 2002

A new modified scheme of the harmonic oscillator approximation (HOA) is reported. Our model takes account of electronic energy-band structures of the medium and simultaneously fits the first three numerical derivatives of the dielectric function with respect to photon energy. Using an extension δ function which is characterized by a parabolic function of k to represent the joint density of states J(E) in the vicinity of critical points, a simple modified factor for the harmonic oscillator approximation is introduced. This modification significantly improves the fits for the dielectric functions of GaAs, InP and GaP over the entire range of photon energies, including the lowest band gaps E
0. It also yields simultaneous fits to the dielectric functions of GaAs, InP and GaP and their first three numerical derivatives with respect to photon energy.
Characterization of Annealed Low-Temperature GaAs Layers Grown by Molecular Beam Epitaxy with n-i-n Structure
Authors: Tsai-Cheng Lin Tsai-Cheng Lin , Tsugunori Okumura Tsugunori Okumura
Published: October 2002

Deep levels and resistivity in annealed low-temperature molecular beam epitaxial (LT-MBE) GaAs layers were characterized using n- i-n structure. We found that annealing at 620°C resulted in the highest attainable resistivity of LT GaAs layers. However, deep-level transient spectroscopy (DLTS) and photocapacitance quenching measurements showed no signal of the midgap (EL2) level. Only a “shallower” EL3-like level was observed in the layer of high resistivity. The fact that no midgap level was detected in the highest-resistivity LT GaAs layer means that the “compensation" mechanism does not play an important role in controlling the semi-insulating properties of LT GaAs layers. On the other hand, a midgap level appeared upon annealing at higher than 620°C, although the resistivity of LT GaAs layers decreased more than five orders of magnitude. The photoquenching measurements suggest that this level is identical to the EL2 level. These results support the “buried Schottky barrier" model.