The influence of ambient gas atmosphere on the liquid and solid composition at liquid phase epitaxial growth of GaAs–Alx-Ga1−xAs layers

Epitaxial gallium arsenide and gallium aluminium arsenide layers were grown from gallium solution on chromium-doped semi-insulating gallium arsenide. The effect of residual water concentration in the ambient gas atmosphere on change of aluminium in Al_xGa_1−xAs was determined. It was shown that a water concentration less than 5 ppm is necessary to grow epitaxial layers with high reproducible XAlAs-content and low carrier concentration.     

EPD investigation in LEC-grown silicon-doped gallium arsenide

The EPD distribution is investigated in silicon-doped LEC-grown gallium arsenide crystals, 30 ÷ 40 mm in mainbody diameter and weighing within 300 ÷ 500 grams. The silicon-doping-dependent hardening effect, previously observed in S-doped and Bridgman grown silicon-doped gallium arsenide is here confirmed. The EPD decreasing with silicon-doping increase is observed to be less pronounced than in the case of S-doped and Bridgman grown silicon-doped samples and possible reasons for this different behaviour are discussed. In any case, a large microprecipitate density together with the EPD reduction appears as a clustering of shallow-pits around dislocation pits.     

Device quality epitaxial gallium arsenide grown by the metal alkyl-hydride technique

Good vapour-phase epitaxial gallium arsenide on gallium arsenide can readily be obtained using trimethylgallium and arsine. The system is rapid and economical to use. Undoped material can be n or p-type with a carrier concentration of less than 5 × 10¹⁵ cm^?3. The best n-type material had a room temperature mobility of 6260 cm² sec^?1 V^?1, and for the best p-type material it was 385 cm² sec^?1V^?1. Material can be controllably doped n-type with sulphur. Multiple sub-micron n⁺ and n on p layers have been grown and used to fabricate Schottky barrier field effect transistors (FET). Material with good photocathode properties was grown by doping strongly p-type with dimethyl zinc.     

Selected 3d-Transition Metals in Gallium Antimonide: Vanadium,Titanium and Iron

3d-transition metals are known to produce deep levels in III-V semiconductors like gallium arsenide or indium phosphide. In this work, gallium antimonide was doped with the most promising candidates vanadium, titanium and iron according to the predictions of the energetic positions of the 3+/2+-charge transfer levels in the bandgap. For optimum incorporation of dopants several growth methods (travelling heater method THM, Czochralski CZ and liquid phase electroepitaxy LPEE) were used. The grown crystals were characterized by photoluminescence and electrical measurements. No deep levels in the forbidden band were found in the case of vanadium and titanium. Vanadium shows a scavenging effect on unintentional impurities. Titanium tends to form inclusions. In gallium antimonide doped with iron an acceptor was found with an activation energy of 26 meV. The findings support the predictions of Tersoff concerning charge transfer levels.     

Growth of quantum wire structures by selective area chemical beam epitaxy

Selective area growth on silicon dioxide masked gallium arsenide substrates by chemical beam epitaxy is used to fabricate inverted V-shaped mesas. Indium gallium arsenide quantum wells grown on top of these mesas form quantum wire structures. The faceted mesa sidewalls are described as a function of substrate temperature and V/III ratio in terms of a simple geometric model. The photoluminescence spectra show that the wire structure peak is shifted to longer wavelength compared to unpatterned substrates, for all growth temperatures. This shift is explained by the migration of indium. For low temperature growth, a second peak due to sidewall quantum wells is observed.     

GaAs/Ga2O3复合多晶薄膜的生长与光学性能研究

采用热蒸发沉积法,以砷化镓和氧化镓粉末为原料,以氧化铟为催化剂,在800 ℃的氩气气氛中,在(100)砷化镓基片表面上沉积生成GaAs/Ga2O3薄膜.以配有成分分析的场发射扫描电镜(FESEM)、X-射线衍射仪(XRD)、光致发光仪(PL)等测试方法对所得薄膜的成分、形貌、晶体结构和光学性能进行了表征.研究结果表明:薄膜以规整的波浪形均匀地覆盖在砷化镓基片表面上,所得薄膜为GaAs/Ga2O3复合多晶薄膜,光致发光峰为强的红光发射;薄膜的生长机理为固-气-固过程,薄膜中砷元素含量的增加与氧化铟的作用有关.     

GaN/GaAs(1 0 0) superlattices grown by metalorganic vapor phase epitaxy using dimethylhydrazine precursor

Superlattices of cubic gallium nitride (GaN) and gallium arsenide (GaAs) were grown on GaAs(1 0 0) substrates using metalorganic vapor phase epitaxy (MOVPE) with dimethylhydrazine (DMHy) as nitrogen source. Structures grown at low temperatures with varying layer thicknesses were characterized using high resolution X-ray diffraction and atomic force microscopy. Several growth modes of GaAs on GaN were observed: step-edge, layer-by-layer 2D, and 3D island growth. A two-temperature growth process was found to yield good crystal quality and atomically flat surfaces. The results suggest that MOVPE-grown thin GaN layers may be applicable to novel GaAs heterostructure devices.     

The role of structural defects in diffusion of elements of group VI in semi-insulating gallium arsenide crystals

The combined effect of the changes in the number and type of vacancies and dislocation density on selenium and sulfur diffusion in single crystals of undoped semi-insulating gallium arsenide has been studied. The differences in the diffusion mechanisms in the subsurface region of samples with an initial deficiency in gallium or arsenic are established as well as the dependence of the effective radius of arsenic trapping by dislocations on the ratio of the concentrations of gallium and arsenic vacancies.     

Polycrystallinity in Gallium Arsenide Crystals Grown by the Czochralski Method

Crystallography Reports - The specific features of the formation of crystallites in gallium arsenide crystals grown by the Czochralski method have been investigated. The crystallites are found to...     

Structural Features Associated with Twinning in the Growth of Gallium Arsenide Single Crystals by the Czochralski Method

Crystallography Reports - The structural features induced by twinning in tin- and tellurium-doped gallium arsenide crystals during their growth by the Czochralski method with liquid melt sealing by...     

Growth of gallium antimonide epitaxial layers on indium arsenide substrates

In the present work the possibility is demonstrated of growing gallium antimonide epitaxial layers on indium arsenide substrates using the liquid phase epitaxial (LPE) method. The influence is nivestigated of the growth conditions on the morphology of the surface and interface of the epitaxial structures InAs GaSb. The optimum technological regimes for growth of heterostructures in the system InAs GaSb are found.     

Effect of electrical field on growth of gallium arsenide layers from vapour phase

The effect of electrical fields on the growth rate and morphology of gallium arsenide layers in the GaAs AsCl₃ H₂ system is investigated. The fields both parallel and perpendicular to the substrate surface are used. It is found that application of the parallel field results n increase of growth rate of (111)A face but does not change that of 2° (001). The morphology of layers grown in such a field is better than that grown without any. The application of perpendicular field results in decrease of growth rate for both crystallographic orientations, the layer morphology worthening. In both cases the effect is greater when the substrate has a negative potential. Possible mechanisms of the field influence on the growth rates of gallium arsenide layers are discussed such as: supersaturation decrease because of nucleation in vapour phase and the change in the rates of surface processes.     

Structure defects investigation of GaAs and AlxGa1−xAs epitaxial layers

The paper is concerned with the results of investigation of structure defects in gallium arsenide and Al_0.3Ga_0.7As epitaxial layers. It was found that structure defects in layers under investigation are responsible for the excess component of the Schottky diode's reverse current.     

A theoretical treatment of GaAs growth by vapour phase transport for {001} orientation

The normal growth rate of a {001} face has been theoretically studied; by considering either direct fixation of gallium arsenide molecules, or formation of intermediate surface compounds. From the theory of rate processes, it appears that experimental results can be interpreted by considering the reactions of desorption of the chlorine atoms adsorbed on surface as limiting the growth. A theoretical expression of the normal growth rate based on desorption by hydrogen has been performed. The descending portions of the curves with decreasing substrate temperature or increasing partial pressure of gallium monochloride, appear as due to an increasing coverage of surface with gallium monochloride molecules. Absolute theoretical values agree with experimental published measures, except for the weakest substrate temperatures. This disagreement may be due to the possibility of desorption of two chlorine atoms by gallium monochloride and formation of gallium trichloride molecules.     

Die Präparation von GaAs-Substraten,untersucht mit Reflexionselektroneninterferenzen

The RHEED-method is used for the examination and characterization of gallium arsenide substrates. It is shown the use of both beam focussing at the object and at the photoplate in studying this subject. It was found that the samples after abrasive cutting and machine lapping give interference patterns of mechanical damaged surfaces with characteristical features. Lap polished surfaces give Kikuchi pattern and a rel-rod pattern of perfect single crystal which is nearly smooth in the atomic level. Critical remarks are given on the Kikuchi pattern as a feature of perfection of the crystal. Results on the penetration depth of rough defects due to machine lapping are in good agreement with data from literature.     

Versetzungsnachweis auf {100}-Flächen von GaAs-Einkristallen

For the measurement of etch pit densities of gallium arsenide crystals of the orientation 〈100〉 the etching in KOH-melts is used proposed by GRABMAIER and WATSON . Metallographical and X-ray topographical investigations of the temperature dependence of this etching and of the correlation between etch pit and dislocation are described. The results verify the exact proof of dislocations in GaAs-〈100〉-crystals.     

Precipitation of supersaturated chromium solutions in gallium arsenide

Transmission electron microscopy has been used to investigate precipitation processes in gallium arsenide doped with chromium and Cr₂O₃. Whatever the doping technique, at concentrations of chromium 4 × 10¹⁶ cm⁻³ the solid solution was observed to contain precipitates which grew, at least partially, due to the migration of substitutional atoms and their transformation into the precipitates. The process is accompanied by generation of vacancies from dislocation loops.     

Effects of melt composition on structural and electrical characteristics of LEC Si-doped gallium arsenide

The aim of this paper is that of briefly reviewing the experimental observations carried out on Si-doped gallium arsenide grown from off-stoichiometry melts (either Ga- or Asrich) in the author's laboratory. It will be shown that the melt composition strongly affect the electrical (electron mobility, density of deep levels) and structural (dislocation density, precipitates) properties of the bulk crystals which proves the existence of a link between point defects and physical and crystallographic characteristics. The experimental results will be discussed considering recent literature reports on point defects in bulk GaAs.     

Raman study of gallium arsenide thin films

The influence of deposition parameters on the structure of the gallium arsenide thin films was investigated by Raman scattering. The study was based on the analysis of the first-order Raman spectra which allows for a differentiation between the amorphous component and crystallites of various sizes. The amorphous and crystalline volume fractions were calculated from the integrated intensities of the deconvoluted peaks. It was demonstrated that a transition occurs from μ-GaAs to a-GaAs for particular plasma conditions and substrate temperature. As a function of the deposition parameters the entire range from mostly microcrystalline to completely amorphous films can be obtained. These properties were consistent with the results obtained on the same samples by transmission high-energy electron diffraction and conventional transmission electron microscopy.     

Influence of non-stoichiometry on the recombination activity of dislocations in undoped semi-insulating GaAs crystals

The effect of non-stoichiometry of gallium arsenide melt composition on the recombination activity of dislocations in undoped semi-insulating GaAs crystals is studied and analyzed. It is shown that the deviation from the stoichiometric melt composition is one of the major factors affecting the recombination activity of dislocations in undoped semi-insulating GaAs crystals. namely: the recombination activity of dislocations is increased when the arsenic-rich melt is used, and, on the contrary, is decreased when the gallium-rich melt is used. The regularities observed are explained by the complex processes of interaction of dislocations with the non-stoichiometry-induced intrinsic point defects.