bluuebunny/crossref_metadata_2025 huggingface dataset:
Behaviour of Implanted Hydrogen in Gallium Phosphide Single Crystals
Authors: Zavada J. M. , Wilson R. G. , Novak S. W. , Pearton S. J. , Von Neida A. R.
Published: March 2011

In this paper we report on the depth distributions of implanted hydrogen in GaP crystals and the subsequent changes produced by post- implantation furnace annealing. A sulfur doped n+ GaP wafer has been implanted with 333 keV protons to a fluence of 5E15/cm+2. A similar wafer was implanted with 350 keV deuterons to the same fluence. Portions of each wafer have been furnace annealed at temperatures up to 500°C. The implanted hydrogen and the dopant S atoms were then depth profiled using secondary ion mass spectrometry (SIMS). The measurements show that the redistribution of hydrogen begins with annealing at about 300°C and proceeds both towards the surface and deeper into the substrate. The overall behavior is similar to that found previously for hydrogen in GaAs. However, in GaP crystals this redistribution begins at a higher temperature and proceeds more slowly in the implanted region. Based on the SIMS profiles, diffusion coefficients for hydrogen migrating into substrate are obtained.
Rapid Thermal Techniques for Zinc Diffusion and Metal/Gallium Arsenide Alloying to Produce Low Resistance Ohmic Contacts
Authors: Rajeswaran G. , Lawrence D. J. , Lee S.-Tong , Kahen K. B.
Published: March 2011

Rapid thermal processing has been utilized to diffuse Zn into GaAs from a thin film zinc silicate source prepared by atmospheric pressure chemical vapor deposition (CVD). The zinc source was capped with ∼500 Å of silicon dioxide (SiO2 ). At 750°C for 20 sec, the diffusion of Zn reached a depth of 0.8 μm. For these diffusions, the diffusion constant is concentration dependent and is proportional to the square of the Zn concentration. Above 7500 C, anomalous secondary diffusion fronts were observed in the Zn diffusion profiles. A new model is proposed that explains the diffusion profiles at all temperatures. Ohmic contacts have been made to the above Zn-diffused surfaces using Cr/AuZn/Au metallizations. A typical value of the specific contact resistance is 8.0 × 10−7 ohm-cm2.
Fabrication and Electrical Properties of MBE Grown Metal-Gallium and Metal-Arsenic Compounds on Ga1-xAlxAs
Authors: Palmstrøm C.J. , Garrison K.C. , Fimland B.-O. , Sands T. , Bartynski R.A.
Published: March 2011

Films of CoGa and CoAs have been deposited on Ga1-xAlxAs surfaces. CoAs films were found to be highly textured, but not single crystal. For CoGa films, however, single crystal growth was observed. The crystalline quality of the (100) oriented CoGa was good as determined by Rutherford backscattering with channeling measurements (χmin ∼7%) and cross-sectional transmission electron microscopy. Schottky barrier diodes fabricated from (100)CoGa/Ga1-xAlxAs and CoAs/Ga1-xAlxAs showed good characteristics with low ideality factors, n<1.15. Good Schottky barrier behavior was also found for (100)ErAs/GaAs structures.
Ion Damage Studies in GaAs-Algaas Ultra-Narrow Wires
Authors: Cheeks T. L. , Roukes M. L. , Scherer A. , Van Der Gaag B. P. , Craighead H. G.
Published: March 2011

Low energy ion damage effects have been investigated in GaAs-A1GaAs two dimensional electron gas (2DEG) materials. The effect of ion mass (He, Ar, Xe) and adsorbed C12 on the charge carrier density and mobility has been studied for ion bombarded 2DEG systems. The 2DEG mobility was significantly reduced by ion damage with the effect becoming more dramatic with smaller ion mass. For the same treatment, the two dimensional carrier density was relatively unaffected. The results of He ion exposure showed serious degradation of the 2DEG with moderate ion dose. Electrical measurements were performed to determine the conducting widths of narrow patterned wires. For the same structural widths (mask width) He defined wires showed smaller electrical widths than Ar milling in the presence of chlorine. Serious limitations to patterning small structures may be imposed using beam processes that include He or other light mass species.
Models and Mechanisms of III-V Compound Semiconductor Growth by Movpe
Authors: Jensen Klavs F. , Mountziaris Triantafillos J. , Fotiadis Dimitrios I.
Published: March 2011

A kinetic model for metalorganic vapor phase epitaxy (MOVPE) of GaAs from trimethylgallium and arsine is imbedded into two-dimensional transport phenomena descriptions of horizontal and vertical MOVPE reactors. The mechanism involves 15 gas-phase species, 17 gas-phase reactions, 9 surface species and 26 surface reactions. The surface reactions take into account different crystallographic orientations of the GaAs substrate. Carbon incorporation is predicted to occur via carbene containing species. A sensitivity analysis shows that only a few reactions are needed to simulate observed growth rates while the full mechanism is important in computing carbon levels in GaAs. The model predictions are in good agreement with data for trimethylgallium decomposition in hot isothermal tubes, with GaAs growth in horizontal reactors, and with carbon incorporation in vertical reactors. The transport-reaction model demonstrates that both gas-phase and surface reactions as well as transport phenomena are important in predicting MOVPE reactor performance.
Purity and Uv Absorption Cross Sections of TMA, TMG, and TMAs
Authors: Okabe Hideo , Emadi-Babaki M.K.
Published: March 2011

Vapor pressures of commercial electronic grade TMA,.TMG and TMAs samples have been measured at various temperatures and compared with those of known pure samples. Only TMA showed the presence of impurities. The UV absorption spectrum of impure TMA shows toluene to be an impurity. The UV absorption cross sections of TMA, TMG and TMAs have been measured and tabulated at several wavelengths.
Quantum-Confined Optical Interband Transitions in 5-Doped Doping Superlattices
Authors: Schubert E. F. , Harris T. D. , Cunningham J. E.
Published: March 2011

Optical absorption and photoluminescence experiments are performed on GaAs doping superlattices, which have a δ-function-like doping profile of alternating n-type and p-type dopant sheets. Absorption and emission spectra reveal for the first time the clear signature of quantum-confined interband transitions. The peaks of the experimental absorption and luminescence spectra are assigned to calculated energies of quantum-confined transitions with very good agreement. It is shown that the employment of the δ-doping technique results in improved optical properties of doping superlattices.
Molecular Beam Epitaxical Growth of AlxGa1-xAs on non- Planar Patterned GaAs (100)
Authors: Guha S. , Madhukar A. , Kaviani K. , Chen Li , Kuchibhotla R. , Kapre R. , Hyugachi M. , Xie Z.
Published: March 2011

We have examined some aspects of inter-facet migration during molecular beam epitaxical(MBE) growth of AlxGal-xAs on patterned GaAs (100) substrates. Scanning and cross-sectional transmission electron microscopy are employed to examine the evolution of the growth front profile. We observe significant inter facet migration from (3111/1411) facets which originate from the terrace edges to the flat terrace region. The migration length of cations on these facets is at least 0.9 μm for GaAs growth while for A10.5Ga0.5As it is less than 0.3 μm. We also observe a decreasing inter- facet migration rate with increasing growth. This interfacet migration is exploited for in situ, growth kinetics controlled, creation of laterally confined quantum well structures on the top terrace region and photoluminescence results for these structures are presented.
Heteroepitaxy of III-V Compounds on Si Substrates for Solar Cells and Led
Authors: Yamaguchi Masafumi , Kondo Susumu
Published: March 2011

Heteroepitaxial growth of GaAs, InP, GaP and InGaP on Si substrates is studied using MOCVD (Metal-Organic Chemical Vapor Deposition). High qgaliti GaAs films on Si, with a dislocation density of about 106 cm−2, are obtained by combining strained- layer superlattice insertion and thermal cycle annealing. Reduction of dislocation density in the III-V compounds on Si is discussed based on a simple model, where dislocation annihilation is assumed to be caused by dislocation movement under thermal and misfit stress. As a result of dislocation density reduction, high-efficiency GaAs-on-Si solar cells with total-area efficiencies of 18.3% (AMO) and 20% (AM1.5), and red and yellow emissions from InGaP-on-Si light-emitting diodes (LEDs) have been realized.
High 2Deg Mobility and Fabrication of High Performance AiGaAs/GaAs Selectively Doped Heterostructure Transistors and Ring Oscillators on Si Substrates
Authors: Chand Naresh , Ren F. , Ziel J. P. Van Der , Chen Y. K.
Published: March 2011

We report growth by MBE and fabrication of state-of-the-art AlGaAs/GaAs selectively doped heterostructure transistors (SDHT's) and ring oscillators on Si substrates. In MBE growth, use of minimum As4/Ga flux ratio during initial nucleation combined with in-situ thermal cycles gave a marked improvement in material quality. Although undoped GaAs buffer layers were highly resistive and were fully depleted under a Schottky contact, a parallel n-type conduction path confined in a thin region (<0.1 pm) near the GaAs/Si interface was sometimes observed whose sheet density (1012 - 1013 cm−2) and mobility (600-900 cm2V−1 s−1) were independent of temperature between 77K and 300K. This parallel conduction did not affect the dc behavior and switching speed of SDHT's, and it was successfully prevented by doping the GaAs with Be near the interface. For a 2DEG sheet density of 1012 cm−2, a mobility as high as 53,500 cm2V−1s−1 at 77K was obtained, as against a mobility of ∼70,000 cm2 V−1 s−1 for a similar structure on GaAs substrates. For 1 μm-gate-length devices, maximum transconductances of 220 and 365 mS/mm were measured at 300K and 77K, respectively. A minimum propagation delay time, Td, of 28 ps/stage was measured at 300K for direct coupled FET logic (DCFL) ring oscillators for 1.1 mW/stage power dissipation. rd reduced to 17.6 ps/stage at 77K. From microwave S-parameter measurements at 300K, current gain and power gain cutoff frequencies of 15 GHz and 18 GHz, respectively, were measured. These results are comparable to the SDHT technology on GaAs substrates.
Reduction of Thermal Stress in Mbe Grown GaAs/Si by Patterning
Authors: Ziel J. P. Van Der , Chand Naresh , Weiner J. S.
Published: March 2011

The biaxial tensile stress of 2.65 kbar in as-grown GaAs/Si for T < 100K is reduced by post-growth patterning of the GaAs and the reduction in stress, as determined by photoluminescence and cathodoluminescence, is dependent on the pattern size and shape. For stripe patterns less than 15 gm wide the stress is largely uniaxial with stress relief normal to the stripe direction. Rectangular patterns exhibited stress relief in orthogonal directions, and a 9 x 12 µm2 rectangle exhibited an average stress of 0.5 kbar. For as-grown GaAs/Si layers 0.9 to 3.25 µm thick, the stress is weakly dependent on layer thickness. For T > looK the stress in as-grown GaAs/Si is reduced and at 295K a value of 1.51 ± 0.21 kbar is obtained. With patterned growth, using a native SiO2 mask, no reduction in stress was observed irrespective of the pattern size, indicating the importance of free GaAs edges in obtaining stress relief.
Photoelectronic Properties of Low Temperature GaAs Grown on Silicon and GaAs Substrates by Mbe
Authors: Mariella Raymond P. , Morse Jeffrey D. , Aines Roger , Hunt Charles E.
Published: March 2011

The characteristics of GaAs layers grown by MBE at growth temperatures from 200 °C to 400 °C have been evaluated by photoconductivity experiments in order to understand the photoelectronic properties of this material. Low temperature (LT) growth of GaAs on both silicon and GaAs substrates has been investigated in an attempt to better understand the nature of defects which are created in epitaxial layers grown under these conditions. Results from experiments on both annealed and unannealed LT samples indicate that the electronic transport properties of the epilayers can be controlled by selecting the appropriate growth conditions.
Comparison of the GaAs Layers Grown on Porous Si and on Si by Molecular Beam Epitaxy
Authors: Wu B.J. , Wang K.L. , Mii Y.J. , Yoon Y.S. , Wu A.T. , George T. , Weber E.
Published: March 2011

GaAs layers have been successfully grown on tilted (100) Si as well as porous Si substrates by molecular beam epitaxy(MBE). Rapid thermal annealing and vacuum thermal annealing have been used to further improve the quality of the epitaxial layers. We observed that the dislocation density near the interface of the heterostructure is higher for GaAs on Si substrate. Both annealing processes are proven to be useful in improving layer quality, while the vacuum thermal annealing seemed to be more effective in minimizing the residual stress.
Initial Nucleation Studies of Heteroepitaxial GaAs films on Si Substrates by Modulated Molecular Beam Epitaxy
Authors: Lee Henry P. , Lius Xiaoming , Wang Shyh , George Thomas , Weber Eicke R. , Liliental-Weber Zuzanna
Published: March 2011

Nominal 100 Å and 150 Å thick GaAs layers were deposited on Si substrates by a modulated molecular beam technique and normal molecular beam epitaxy (MBE) at 300 °C and 375 °C respectively for plan view and cross-sectional transmission electron microscopy (TEM) examinations. From coverage of Moire fringes, it is found that the nucleated GaAs films grown by the modulated molecular beam technique were thinner, streaker and more two-dimensional than the MBE grown films. The same modulated molecular beam technique was also used for the deposition of the initial buffer layer of 3µm thick GaAs on Si films. Results from the 77k photoluminescence(PL) and double crystal X ray diffraction measurements showed that these films have superior optical and structural quality compared to similar films grown by normal two-step MBE. The improvement is attributed to a more two-dimensional nucleation of GaAs films associated with the modulated molecular beam growth technique.
Dependence of Threading Dislocation Density on Substrate Misorientation in In0.15Ga0.85As Grown on GaAs(100)
Authors: Uppal P.N. , Ahearn J.S. , Herring R.
Published: March 2011

The density and arrangement of dislocations in In0.15Ga0.85As grown on GaAs(100)) were determined by transmission electron microscopy as a function of misorientation toward (111)A, (111)B, and (110). Strained layer superlattices were used in all cases to reduce dislocation density. Layers grown on exact GaAs(100) exhibited a non-uniform threading dislocation dis- tribution whereby some areas had a high density (∼ 109cm-2or higher) of dislocation tangles and other areas that we in between had a more uniform density (∼ 2 x 107cm-2). The misorientated layers exhibited a uniform threading dislocation distribution with densities of ∼ 5 x 106 cm-2 for (100) misoriented towards (111)A, ∼ 1 x 107cm-2towards (111)B, and ∼ 3 x 107cm-2 towards (110). The misfit dislocation network (dislocations located at the GaAs-InO0.15Ga0.85 As interface) formed orthogonal dislocation arrays in the case of exact (100) substrates and slightly non-ortho- gonal arrays in the case of misoriented substrates. These results are explained with the help of a general glide model of strain relaxation in which the exact (100) orientation has eight equally stressed glide systems which presumably activate during strain relaxation. With misoriented substrates the stress symmetry is broken and fewer glide systems experience the maximum stress, thus reducing the number of active dislocation systems. A small asymmetry in interfacial dis- location density was observed in all the cases where the linear dislocation density along the two (011) and (011) orthogonal directions differed by about 20%. This is explained by the preferred activation of (x-dislocations (high dislocation mobility) over 13-dislocations (low dislocation mobility).
High Quality Epitaxial Growth on in-Situ Patterned Inp Substrates
Authors: Temkin H. , Harriott L. R. , Weiner J. , Hamm R. A. , Panish M. B.
Published: March 2011

We demonstrate a vacuum lithography process which uses a finely focused Ga ion beam to write the pattern which is then transferred to the InP pattern by low energy dry etching. Surface steps on the order of 1000-2000A in height, and lateral resolution limited only by size of the ion beam, can be efficiently prepared using moderate Ga ion fluences. The surfaces prepared by this process are damage free and suitable for epitaxial overgrowth. GaInAs/InP heterostructures grown on in-situ patterned substrates show excellent morphology and high luminescence efficiency.
Mbe-Growth of InAs and GaSb Epitaxial Layers on GaAs Substrates
Authors: Söderström J. R. , Chow D.H. , McGill T.C. , Watson T.J.
Published: March 2011

We have grown a number of InAs and GaSb bulk layers on GaAs substrates and studied the properties of the semiconductor films as a function of the various growth parameters. Preliminary results from GaSb growth are presented in addition to an extensive study of InAs growth. The films were characterized during growth by RHEED. RHEED-oscillations were observed during both InAs and GaSb growths. Hall effect measurements yielded peak electron mobilities for InAs of 18,900 cm2/Vs at 300 K and 35,000 cm2/Vs at 77 K. For GaSb the as grown layers were found to be p-type with a carrier concentration of 9x1015cm-3 and a hole mobility of 910 cm2 /Vs at 300 K.
Rheed Measurement and Chemical Kinetics of Chemical Beam Epitaxial growth of GaAs
Authors: Chiu T.H.
Published: March 2011

Recent efforts employing reflection high energy electron diffiaction measurements to study the chemical beam epitaxial growth of GaAs is reviewed. A reaction model which assumes the dominance of Ga alkyls and their derivatives adsorbed on the growing surface can explain most of the growth results in a consistent way. Dynamic evolution of the reconstruction pattern of the adsorbed triethylgallium or trimethylgallium overlayer illustrates how the alkyl-Ga bonds are cleaved sequentially. The growth rate dependence on temperature and incident flux can be fitted quite well in this reaction model. In the absence of As flux, the existence of a metastable Ga alkyl overlayer makes possible the atomic layer epitaxy of GaAs.
Effect of Atomic Hydrogen on Impurity Reduction in Mombe-Grown GaAs
Authors: Kao Y.C. , Kim T.S. , Shih H.D. , Matteson S. , Duncan W.M. , Farrington D.L.
Published: March 2011

In this paper, the effect of atomic hydrogen on carbon impurity incorporation during the metalorganic-molecular-beam-epitaxy (MOMBE) growth of GaAs is studied. Atomic hydrogen was introduced into the MOMBE chamber during the growth by cracking molecular hydrogen with a high temperature cracker cell. Atomic hydrogen appears to be effective in reducing the background doping level of MOMBE-grown GaAs, presumably by reacting with hydrocarbon radicals. Background doping levels as low as 4 × 1014 cm−3 and room temperature hole mobilities as high as 430 cm2/V-sec were achieved. This result demonstrates that it is feasible to grow high quality GaAs films in MOMBE without using AsH3 or a high flux of As4by introducing atomic hydrogen into the chamber during the growth.
Low-Pressure Chemical Vapor Deposition of Polycrystalline Silicon and Silicon Dioxide By Rapid Thermal Processing
Authors: Öztürk Mehmet C. , Wortman Jimmie J. , Zhong Yu-Lin , Ren Xiao-Wei , Miller Roderick M. , Johnson F. Scott , Grider Douglas T. , Abercrombie David A.
Published: March 2011

Low-pressure chemical vapor deposition of polycrystalline silicon and silicon dioxide in a lampheated cold-wall rapid thermal processor have been investigated. Silicon dioxide films have been deposited by thermal decomposition of tetraethylorthosilicate known as TEOS. The technique can be used for rapid deposition of good quality thick passivation layers at moderate temperatures. Polycrystalline silicon depositions have been accomplished using silane (SiH4) diluted in argon as the reactive gas. Surface roughness and resistivity of the films deposited at temperatures above 700°C are comparable in quality to films deposited in a conventional LPCVD reactor at 610°C. In this temperature range, deposition rates as high as 4000Å/min can be obtained.
Polysilicon Emitter Transistors Manufactured using a Novel Limited Reaction Processing System
Authors: Ruddell Fred , Parkes Colin , Armstrong B Mervyn , Gamble Harold S
Published: March 2011

This paper describes a LPCVD reactor which was developed for multiple sequential in-situ processing. The system is capable of rapid thermal processing in the presence of plasma stimulation and has been used for native oxide removal, plasma oxidation and silicon deposition. Polysilicon layers produced by the system are incorporated into N-P-N polysilicon emitter bipolar transistors. These devices fabricated using a sequential in-situ plasma clean-polysilicon deposition schedule exhibited uniform gains limited to that of long single crystal emitters. Devices with either plasma grown or native oxide layers below the polysilicon exhibited much higher gains. The suitability of the system for sequential and limited reaction processing has been established.
Thin Silicon Dioxide using the Rapid Thermal Oxidation Process for Trench Capacitors
Authors: Inoue Morio , Yoneda Kenji
Published: March 2011

Electrical characteristics of trench capacitor using RTO oxide, nitroxide and reoxidized nitroxide as the gate insulator are discussed. High temperature RTO is effective to prevent the oxide thinning at the trench corner and dielectric strength of trench capacitor is improved drastically. The lifetime of trench capacitors using RTO is more than 10 times longer than that of trench capacitors using conventional furnaces. Using reoxidized nitroxide as the gate insulator, higher charge to breakdown is obtained. The RTP is superior to the process using the conventional furnace for gate insulator of trench capacitor. Improvement in temperature uniformity and operation reproducibility are essential to RTP equipments for production use.
Formation of Device Quality Si/SiO2 Interfaces in a Multichamber Integrated Processing System
Authors: Kim S.S. , Tsu D.V. , Lucovsky G. , Fountain G.G. , Markunas R.J.
Published: March 2011

This paper describes the key process steps in the low temperature, <300ºC, formation of device quality Si/SiO2 interfaces employing oxide deposition by Remote Plasma-Enhanced Chemical Vapor-Deposition (Remote PECVD). The quality of the Si/SiO2 interface correlates with the degree of surface reconstruction that is controlled by ex-situ wet cleaning and in-situ Rapid Flash Heating. Electronic properties of the MOS structure also vary with the deposited oxide thickness, independent of the initial surface quality.
(Rapid) Thermal Nitridation of SiO2 films
Authors: Oude Elferink J.B. , Habraken F.H.P.M. , van der Weg W.F.
Published: March 2011

In this paper we report on the composition of thermally nitrided silicon dioxide films on silicon. Nitridation temperatures ranging from 950 to 1150ºC and nitridation times ranging from 10 to 240 s were used. The purpose of this study is to reveal the mechanisms involved in the nitridation process with emphasis on the role of hydrogen. From the temperature dependence of the amount of nitrogen in the films the effective activation energy for nitrogen incorporation in this initial stage was deduced.
Formation of Ultrathin Stacked Dielectrics Prepared by In-Situ Multi-Step RTP-CVD
Authors: Ting W. , Lin S. N. , Kwong D. L.
Published: March 2011

Ultrathin stacked SiO2/Si3N4/SiO2 films have been fabricated successfully using in-situ multi-step rapid thermal processing chemical vapor deposition (RTP-CVD). Stacked Si3N4/SiO2 (NO) layers were deposited first by RTP-CVD. Some samples were further rapid-thermal oxidized after stacked layer deposition to form oxide/nitride/oxide (ONO) stacked layers. Ellipsometry, Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) were performed to characterize the films. Results show that well defined stacked Si3N4/SiO2 layers were fabricated and for wafers subjected to rapid-thermal oxidation an oxygen-rich SixNyOz layer was formed on the top of the dielectric stack. Nitrogen pile-up at the dielectric/substrate interface was observed for all wafers indicating that nitrogen diffuses into the bottom oxide during nitride deposition even though the deposition temperature is well below those used in thermal nitridation of thermal oxides.
Rapid Thermal Annealing of As in Si
Authors: Shih N.T. , Huang F.S. , Chu C.H. , Chen W.S.
Published: March 2011

The results of a detailed investigation of diffusion of ion implanted As in Si during Rapid Thermal Annealing are reported. A series of experiments has been performed on samples prepared for various thermal treatments, such as peroxidation and preheat. The RTA conditions were chosen at 850°C for 15 seconds in order to study the metastable state. Sample analysis includes depth profiling by RBS and Spreading Resistance measurements, electrical characterization employing Hall measurements, and residual defects by cross-section TEM and planar image. The carrier concentration profile shows the different extent of the mixed Gaussian-Chebyshev polynomial distribution for various prepared samples. We believe the neutral interstitial state I°(Si) survives during RTA for asreceived samples. It gives a Gaussian curve in As profile. The denuded region produced after thermal treatments reduces the oxygen content and creates less 1°(Si) during SPE. So the Gaussian-Chebyshev polynomial distribution was obtained. From the above study, we believe the Gaussian profile can be obtained by controlling RTA conditions This Gaussian-like profile can also suppress hot electron effects by its smooth gradient (generating small electric field) near drain and large overlap under spacer (making large electric field away from gate). So we fabricated rapid thermal annealing singlediffusion drain n-MOSFET. The reduction of hot electron effects was studied, too.
Rapid Annealing of Rie-Induced Damage in GaAs and AlGaAs
Authors: Pearton S. J. , Hobson W. S. , Chakrabarti U. K. , Short K. T. , White A. E. , Jones K. S.
Published: March 2011

Ion bombardment of the surface during CCI2 F2:O2 or C2 H6:H2 :Ar reactive ion etching of GaAs and AlGaAs can produce a heavily disordered near-surface (∼1000A for 380V self-bias on the cathode in a parallel plate reactor) region. The damage in this layer causes carrier depletion effects due to trapping of deep level defects. We have investigated the in-situ and post-RIE annealing of both the structural disorder and the electrical effects of the damage using TEM, ion channelling, C-V and I-V measurements. Etching at 400°C reduced the RIE-induced damage due to dynamic annealing processes. Carrier reductions of approximately an order of magnitude were observed immediately after etching GaAs and AIGaAs in C2H6:H2:Ar; much smaller changes (∼20%) were observed using CCI2F2:O2. For both gas chemistries annealing in the range 200–300°C produced the most ideal I-V characteristics in GaAs, whereas 300–400°C was required for AIGaAs.
Effects of Rapid Thermal Processing on Mbe GaAs on Si
Authors: Ito A. , Kitagawa A. , Tokuda Y. , Usami A. , Kano H. , Noge H. , Wada T.
Published: March 2011

Variations of electron traps in molecular-beam-epitaxial (MBE) GaAs layers grown on Si substrates by rapid thermal processing (RTP) have been investigated with deep level transient spectroscopy (DLTS). RTP was performed at 760 – 910 °C for 9s with Si02 encapsulant. In contrast with the layer on GaAs, the traps AI(Ec – 0.65eV) and A2(Ec – 0.81eV) are observed in the layer on Si. The trap EL2h, one of the EL2 family, is produced by RTP in the layer on Si. Some GaAs surfaces were etched to prove the deeper region. In the surface region, the concentrartion of EL2h is comparable to that of EL2 produced by RTP in the layer on GaAs. On the other hand, in ∿ 1 μm below the surface, the concentration of EL2h is about ten times as large as that of EL2. It is speculated that the stress from the GaAs/Si interface enhances the production of the EL2h concentration. In addition to the EL2, the traps R1(Ec – 0.23 eV), R2(Ec – 0.40 eV), R3(Ec – 0.43eV) and R4(Ec – 0.56 eV) are produced by RTP in the GaAs grown on Si.
Epitaxial Growth of Sil-xGex/Si Heterostructures by Limited Reaction Processing for Minority Carrier Device Applications
Authors: King C. A. , Hoyt J. L. , Noble D. B. , Gronet C. M. , Gibbons J. F. , Scott M. P. , Laderman S. S. , Kamins T. I. , Turner J.
Published: March 2011

In an effort to extend the performance limits of semiconductors, devices based on heterojunctions rather than homojunctions are being investigated with great interest. Heterojunctions allow certain device design constraints to be relaxed because the charge distribution, electric field, and potential can be tailored extensively, permitting better device structures to be utilized. Silicon technology today enjoys a firm grip on a large portion of the electronics industry due in part to its superior material properties.
Focused Ion Beam Induced Deposition
Authors: Melngailis John , Blauner Patricia G.
Published: March 2011

Focused ion beam induced deposition is already in use commercially for the repair of clear defects in photomasks, where missing absorber is added. Research is being carried out to extend this technique to the repair of x-ray lithography masks and to the restructuring and repair of integrated circuits, particularly in the prototype phase. In this technique a local gas ambient is created, for example, by aiming a small nozzle at the surface. The gas molecules are thought to adsorb on the surface and to be broken up by the scanned focused ion beam. A deposit is formed with linewidth equal to the beam diameter which can be below 0.1 Ό m. At small beam diameters and low currents (50–100 pA) the time to deposit 1Όm3 is in the vicinity of 10–20 sec. If the gas is a hydrocarbon, the deposit is largely carbon, which is useful for photomask repair. On the other hand, if the gas is a metal halide or a metal organic, the deposit is metallic. The deposits have substantial concentrations of impurities due to the atoms in the organometallic, to the ion species used, or to the ambient in the vacuum chamber. Thus the resistivities of the "metal" films deposited typically range from 150 to 1000 ΌΏcm which is usable for some repairs. (Pure metals have resistivities in the range 2.5 to 12 pQcm.) We have deposited gold from dimethyl gold hexafluoro acetylacetonate and have achieved linewidths down to 0.1 Όm, patches of 1 Όm thickness with steep side walls and in some cases, resistivities approaching the bulk value. Other workers have reported deposits of Al, W, Ta, and Cr. We will review previous work in the field and present some of our own current results.
Broad and Focused Ion Beam Ga+ Implantation Damage in the Fabrication of p+-n Si Shallow Junctions
Authors: Steckl A. J. , Lin C-M. , Patrizio D. , Rai A. K. , Pronko P. P.
Published: March 2011

The use of focused and broad beam Ga+ implantation for the fabrication of p+-n Si shallow junctions is explored. In particular, the issue of ion induced damage and its effect on diode electrical properties is explored. FIB-fabricated junctions exhibit a deeper junction with lower sheet resistance and higher leakage current than the BB-implanted diodes. TEM analysis exhibits similar amorphization and recrystallization behavior for both implantation techniques with the BB case generating a higher dislocation loop density after a 900°C anneal.
Epitaxial Explosive Crystallization of Amorphous Silicon Layers Buried in a Silicon (100) and (111) Matrix
Authors: Stolk P. A. , Polman A. , Sinke W. C.
Published: March 2011

420 nm thick amorphous Si layers buried in a Si (100) or Si (111) matrix, produced by 350 keV Si-implantation, were irradiated using a pulsed ruby laser. Time-resolved reflectivity measurements show that melting can be initiated buried in the samples at the crystalline-amorphous interface. Melting is immediately followed by explosive crystallization of the buried amorphous layer, which is started from the crystalline top layer. The velocity of this self-sustained crystallization process is determined to be 15.0 ± 0.5 m/s for Si (100) and 14.0 ± 0.5 m/s for Si (111). RBS and cross-section TEM reveal that epitaxially grown crystalline Si, containing a high density of twin defects, is formed in both the Si (100) and the Si (111) sample.
Defects Produced by High Energy Oxygen Ions Implanted in Silicon
Authors: Grob A. , Grob J. J. , Perio A. , Thevenin P. , Siffert P.
Published: March 2011

Rutherford backscattering/channeling analysis was used to study the damage creation processes occuring during 1 MeV O+ implantation in silicon. The target temperature was varied from RT to 500°C using beam heating. The corresponding damage profiles and dechanneling behaviour were studied. Several implantations were performed at 77K for comparison. Transmission electron microscopy observations were connected to the dechanneling measurements in order to determine the dominant kind of defect in each case.

For 77K implants, the defects are mainly interstitials distributed according the energy deposition in elastic collisions, extending up to the surface. At 500°C, the defects are imperfect dislocations confined in a narrow band around the mean range of oxygen ions. We demonstrate that dechanneling in samples implanted at intermediate temperatures results from a mixing of point defects and distorsion centers. The relative importance of the two kind of defects is followed as a function of implantation temperature.
Partially Ionized Beam Deposition of Thin Films
Authors: Lu T.-M.
Published: March 2011

It has been shown recently that using less than a few percent of self-ions, i.e., ions derived from the deposition material itself, (partially ionized beam (PIB) deposition), one can dramatically modify thin film properties. In this paper we discuss phenomena such as surface cleaning, enhanced surface ordering, and ion-induced surface damage associated with PIB-surface interactions. PIB metal deposition has been emphasized.
Compensation :in GaAs/GaAlAs Heterostructures by Ion Implantation Comparison of Oxygen and Boron
Authors: Descouts B. , Tasselli J.
Published: March 2011

Ion implantation has been used to form an insulating layer in GaAs/GaAlAs heterostructures for bipolar transistor applications with the aim of reducing the base-collector capacitance. Two ions have been compared : boron and oxygen. In both cases magnesium has been implanted to contact the base layer and rapid thermal annealing has been used to activate this dopant. We show that the base-collector capacitance can be lowered by a factor of ∼,2 with oxygen, but high oxygen doses (≥, 1014 ions/cm2 ) are necessary to obtain reproducible results. The capacitance is lowere!6 by 2 a factor of ∼4 with optimized boron dose. With high boron doses (≥ 1013 /cm2 ) we have decreased the capacitance by a factor of 16 but the defects created during the implantation affect the properties of the emitter and base layer.
Implant Damage in AlGaAs Based Superlattices and Alloys at 77K
Authors: Dobisz E. A. , Dietrich H. , McCormick A. W. , Harbison J. P.
Published: March 2011

Previously, it was shown that superlattices implanted with Si at 77K, exhibited more extensive damage and uniform compositional mixing upon subsequent annealing than samples implanted at room temperature.[l,2] The current work focuses on the damage in samples implanted with Si at 77K. The study shows that for a given dose, the amount of damage depends upon the layer thickness and the composition. Specimens of bulk GaAs, Al 3Ga. 7As, 7.5 nm GaAs -10 nm Al. 3Ga. 7As superlattice (SL1), 5.5 nm GaAs −3.5 nm AlAs superlattice (SL2), and 8.0 nm GaAs −8.0 nm AlAs superlat-tice (SL3) were implanted at 77K with 100 KeV Si, with doses ranging from 3 × 1013 cm−2 to 1 × 1015 cm−2. The samples were examined by ion channelling and cross sectional transmission electron microscopy (TEM). At 77K and a dose of 1 × 1014 cm−2, the GaAs and SLi showed an amorphous layer, while no damage peak was observed in SL2. The 77K amorphization thresholds of the Al 3Ga. 7As alloy, SL2, and SL3 were 2.5 × 1014 cm−2, 4 × 1014 cm−2, and 1 × 1015 cm−2 respectively. The sharpness of the amorphization threshold varied with the material.
SIMS Determination of MG+ and AS+ Range Profiles in Photoresist and Polyimide Implant Masks.
Authors: Dugger D. L. , Stern M. B. , Rubico T. M.
Published: March 2011

The distribution of Mg+ (a p-type dopant for GaAs) and As+ (an p-type dopant for Si) implanted into both photoresist (PR) and polyimide (PI) have been determined experimentally. Range data of Mg ions at 200 keV and 300 keV and As ions at 150 keV have been measured by Secondary Ion Mass Spectroscopy (SIMS). SIMS values for the projected range Rp and the standard deviation ARp were compared to range profile data calculated using the Projected Range Algorithm (PRAL) of Biersack [1] as well as the standard LSS theory [2]. While the values for Rp calculated from the PRAL model generally agreed within 10% of the SIMS values, the calculations underestimated Rp for PR but were in good agreement for PI. The LSS calculations underestimated Rp in both materials.
Study of Thermodynamic Phase Stability of Intermetallic Thin Films of Pt2Ga, Ptga and PtGa2 on Gallium Arsenide
Authors: Kim Young K. , Shuh David K. , Williams R. Stanley , Sadwick Larry P. , Wang Kang L.
Published: March 2011

Epitaxial thin films of three different Pt-Ga intermetallic compounds have been grown on GaAs by molecular beam epitaxy (MBE). The resultant films have been annealed at various temperatures and then examined using X-ray two-theta diffraction. Both PtGa2 and PtGa thin films are chemically stable on GaAs under 1 atmosphere of N2 up to 450°C and 600°C, respectively. Thin films of Pt2Ga react with GaAs at temperatures as low as 200°C to form phases with higher Ga concentration.
The Effect of Annealing on the Structure of Epitaxial CaF2 Films on Si(100)
Authors: Phillips Julia M. , Palmer J. E. , Hecker N. E. , Thompson C. V.
Published: March 2011

We have studied the effect of different annealing conditions on the crystallinity and morphology of 1000Å epitaxial CaF2 films on Si(100). The crystallinity of the films is improved by the anneals, with the highest anneal temperatures giving the greatest improvement. The results are consistent with the model previously proposed to explain the success of rapid thermal annealing in improving thicker epitaxial CaF2 films.
Effects of Growth Temperature on MOCVD-Grown GaAs-ON-Si
Authors: Nozaki S. , Noto N. , Okada M. , Egawa T. , Soga T. , Jimbo T. , Umeno M.
Published: March 2011

Effects of growth temperature on crystallinity and surface morphology of MOCVD-grown GaAs-on-Si were studied. The FWHM of the (400) x-ray peak in the rocking curve of GaAs-on-Si reduces from 340 to 230 arcs with increasing growth temperature from 650 to 700°C, but further increase of growth temperature does not significantly decrease the FWHM. The surface morphology of GaAs-on-Si grown at higher temperature is scaly and rough. Lower growth temperature is desirable to obtain GaAs-on-Si with good surface morphology. In order to eliminate the trade-off between crystallinity and surface morphology, the three-step growth process is proposed.
Evaluation of Anti-Phase-Boundaries in GaAs/Si Heterostructures by Transmission Electron Microscopy
Authors: Ueda O. , Soga T. , Jimbo T. , Umeno M.
Published: March 2011

The nature and behavior of anti-phase-boundaries in GaAs/Si heterostructures using GaP, GaP/GaAsP and GaAsP/GaAs strained layer superlattices as intermediate buffer layers, have been investigated by transmission electron microscopy. It has been found that anti-phasedomains are very complicated three dimensional polygons consisting of several sub-boundaries in different orientations. Self-annihilation of anti-phase-domains during crystal growth of GaAs on (001)just or (001)2°off Si substrates is directly observed for the first time through planview and cross-sectional observations. Based on these findings, a mechanism of annihilation of these domains is proposed.
Correlation Between Crystallinity and Schottky Diode Characteristics of GaAs Grown on Siby MOCVD
Authors: Egawa T. , Nozaki S. , Noto N. , Soga T. , Jimbo T. , Umeno M.
Published: March 2011

We have studied the crystallinity and Schottky diode characteristics of GaAs/Si grown by MOCVD. In comparison with two-step growth and GaP/strained layer superlattice techniques, the crystallinity and the Schottky diode characteristics are superior for the GaAs/Si with Al0.5Ga0.5P as an intermediate layer. The GaAs/Si grown with the Al0.5Ga0.5 intermediate layer shows mirror—like surface morphology and an X-ray FMHM of 188 arcs. The ideality factor of the Schottky diode fabricated on the GaAs/Si grown with the Al0.5Ga0.5P intermediate layer is 1.06, but its forward current-voltage characteristic shows a significant leakage current at small forward bias. It is also found that the composition of Al affects strongly the crystallinity and the Schottky characteristics of GaAs/Si.
Interfacial Microstructures in InxGa1-xAs/GaAs Strained Layer Structures
Authors: Yao J. Y. , Andersson T. G. , Dunlop G. L.
Published: March 2011

The interfacial microstructures of lattice strained InxGal-xAs/GaAs multiple layer structures, that were grown by molecular beam epitaxy (MBE) on GaAs (100) substrates, have been investigated and characterised by transmission electron microscopy (TEM). A g3ii weak beam imaging technique has been used to study structural imperfections at the heterointerfaces. The morphology of rough heterointerfaces, which resulted from the growth of the InxGal-xAs layers (strained layer) either in a two dimensional (2D) or in a three dimensional (3D) growth mode via island formation, was imaged using this technique. A transition from 2D to 3D growth was found to occur at a certain critical layer thickness which decreased with increasing indium fraction. In thicker layers, dislocation complexes, which may have been caused bythe formation of islands, were also observed. These complexes were primarily composed ofstacking faults bounded by partial dislocations.
A Novel Method for Study of Roughness at Buried Interfaces by Plan View Tem: Si/SiO2
Authors: Gibson J. M. , Lanzerotti M. Y.
Published: March 2011

Interfacial roughness can be measured at buried interfaces using plan view transmission electron diffraction. The method relies on surface termination Bragg reflections and is applied to the Si/SiO2 system. In contrast to other methods, this does not require stripping of the SiO2 overlayer or projection assumptions. We find that thermal oxide interfaces are significantly flatter than previously supposed.

The Si/SiO2 interface has been extensively examined by a wide variety of techniques. A subset of these studies have focussed on the interfacial roughness and it has been shown that increased step density reduces electron mobility.[1, 2 ] Although supporting the correlation of mobility with step density, the data presented here shows thermally oxidized Si/SiO2 interfaces to be significantly flatter than previously assumed.
Position-Sensitive Atom Probe and Stem Analysis of the Microchemistry of GaInAs/Inp Quantum Wells
Authors: Liddle J. Alex , Long N.J. , Norman A.G. , Cerezo A. , Grovenor C.R.M.
Published: March 2011

The recently developed techniques of pulsed laser atom probe microanalysis (PLAP) and position sensitive atom probe (POSAP) have been applied to the study of quantum well interfaces in samples that have also been well characterised by the more conventional techniques of TEM and STEM. These techniques have the potential for providing chemical information with a spatial resolution of better than 2nm, but the atom probe has the ability to independently resolve morphological and microchemical features of interfaces in three dimensions.

This paper presents results taken from GaInAs/lnP MOCVD-grown samples, comparing information on well composition, and on the chemical abruptness and morphological roughness of interfaces using complementary analysis techniques. We have concentrated on obtaining reliable quantitative data on the phosphorous content of the GaInAs wells and on the gallium and arsenic contents of the InP barrier layers.
Correlation Between Defect Production and Excitonic Emission in the Irradiated ZnSe-ZnS Strained-Layer Superlattices
Authors: Sekoguchi Maki , Taguchi Tsunemasa
Published: March 2011

The effects of thermal heat-treatment, N+ -ion, Ar+ -ion, γ-ray and electron-beam irradiations have been studied on MOCVD-grown ZnSe-ZnS strained-layer superlattices (SLSs) by means of low-temperature photoluminescence and X-ray diffraction measurements. As-grown SLS structure seems to be stable against the heat-treatment compared to ZnSe thin film, but after the defects are introduced in the SLS by irradiation, additional fluctuation at the interface between the ZnSe well and the ZnS barrier layers takes place. However, no significant intermixing and the changes of strain can be detected in the irradiated SLS.
Deep Level Transient Spectroscopy of Defects Induced by the Combination of CF4Reactive Ion Etching and Oxidation in Metal-Oxide-Silicon Capacitors.
Authors: Vuillaume Dominique , Gambino Jeff P.
Published: March 2011

Metal-Oxide-silicon (MOS) capacitors have been fabricated on CFbreactive ion etched silicon (n and p types) in order to study the defects at the Si-Si02interface and in the bulk of the substrate, produced by the combination of reactive ion etching (RIE) and oxidation. Bulk defects and fast interface states are analysed by Deep Level Transient Spectroscopy (DLTS) and the slow interface states in the oxide layer near the interface are probed by Tunnel-DLTS. A density of fast interface states in the range 1010-1011cm−2eV−1is observed for capacitors (both n and p types) fabricated with either dry or wet oxidations, and is probably due to disrupted or strained bonds at the Si-SiO2interface. The observation of bulk defects in the wet-RIE oxide samples but not in the dry-RIE oxide samples may be related to the shorter oxidation time for wet oxides (31mn) compared to dry oxides(190mn) and explained by a greater annealing of RIE induced defects during the dry oxidation. The bulk traps are identified to be related to carbon contamination, in SiC form, introduced during RIE. Finally, an increase of the slow interface states density is observed for the n-type dry oxide samples.
Interaction of Oxygen with Native Chemical Defects in CuInSe2 Thin Films
Authors: Noufi Rommel , Cahen David
Published: March 2011

We formulate a consistent defect chemical model of the effect of air/02 anneals on CuInSe2 polycrystalline thin films. The model centers on O-induced neutralization of (near) surface donor states in CuInSe2 grains. The simplest identification of these states is with ionized Se vacancies, due to coordinatively unsaturated In on grain surfaces and boundaries.
A Model for Interdiffusion at Metal Semiconductor Interfaces: Conditions for Spiking
Authors: Hellman Olof C. , Herbots Nicole , Eng David C.
Published: March 2011

We have derived a dynamical model for interdiffusion at aluminum-silicon interfaces which can explain the great variety of rates of interdiffusion observed for this system. The variables addressed by the model include the degree of covalent bonding which occurs at the chemical interface and the local atomic structure of that interface. Local solid solubility data and maximum rates of dissolution are derived analytically, and good agreement is observed between the model and both thermodynamic data for the bulk aluminum-silicon system and kinetic data for reaction rates at differently prepared interfaces. The influence of dopants and structural defects on the predictions of the model is in accord with experimental observations. The model points to some critical conditions for the preparation of thermally stable aluminum-silicon interfaces, which are potentially applicable to other metal-semiconductor systems.