Porous gallium arsenide with arsenic clusters

It is for the first time that the possibility is demonstrated of preparing gallium arsenide with arsenic clusters under conditions of annealing of its porous layers obtained by electrochemical etching. It is found that the clusters are concentrated in porous layer barriers, their size ranges from 1 to 10 nm, and the density reaches 4×10¹⁸ cm⁻³. Under conditions of annealing in the temperature range from 400 to 600°C, an improvement in the structure quality of the porous layer is observed, and the lattice parameter (reduced for this layer) increases to approach a value characteristic of a single crystal. When highly alloyed substrates of the n-type are used, the inversion of the type of conductivity is observed in the surface part of the porous layer, which is due to the emergence of deep-lying acceptor centers. Thermal annealing leads to a narrowing of the inversion layer and to a more uniform distribution of electrically active centers over the porous layer thickness.     

The annealing of damage in ion implanted gallium arsenide

Photoluminescence measurements at 77°K and Rutherford scattering of 450 keV protons were used to study radiation damage and annealing in ion implanted GaAs. The characteristic band edge luminescence (8225 Å) in GaAs is completely quenched by ion implantation. Photoluminescence measurements on samples which were isochronally annealed show a single annealing stage at 600°C. A luminescence peak at 9140 Å is introduced into the spectra of all implanted and annealed samples. This peak is attributed to an acceptor level created by As vacancies. The intensity of the peak is greatly reduced by protecting the surface of implanted layers with SiO₂ during annealing. Rutherford scattering measurements on isochronally annealed samples reveal two annealing stages. A 300°C annealing stage is observed on samples which have an initial aligned yield less than random while a 650°C stage is observed on samples which have an initial aligned yield equal to random.     

Microdoping of subsurface gallium arsenide layers with hydrogen ions

A method of microdoping subsurface semiconductor layers with hydrogen ions (protons) with the use of a plasma-beam discharge is suggested. The method was tested on gallium arsenide layers and was proven to be more efficient than other well-known methods used for modifying subsurface layers.     

Behavior of silicon implanted in gallium arsenide during a radiative anneal

We have studied the activation of silicon implanted in GaAs during a rapid thermal anneal with a protective layer and without it. It is found that during the anneal there is a diffusion redistribution of the silicon. The use of a dielectric coating during the anneal leads to a reduction both in the diffusion coefficient and also in the amount of electrical activation of the impurity. Tomsk Polytechnical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 44–48, November, 1998.     

Enhancement of the Kerr effect in magnetooptical DyFeCo/GeO carriers

The optimum parameters of a dielectric layer near the substrate in the interference multilayer structure are calculated. The calculations showed that this layer should have the index of refraction n∼3. The results are presented of measuring the Kerr angle of magnetooptical rotation in the multilayer structure, in which GeO films were used as dielectric layers for the first time. The maximum Kerr angle of rotation and magnetooptical quality observed in this system were 0.75° and 0.34°, respectively. These values exceed those inherent in the known information carriers, which demonstrates the advantage of this structure for use in magnetooptical discs.     

Effect of radiation annealing on activation of silicon implanted in gallium arsenide

We have investigated the profile of²⁸Si implanted in GaAs obtained by radiation annealing using an electron beam (P=7.6 W/cm², E=10 keV, t=10 sec, T≅750°C) and thermal annealing in a furnace (T=800°C, t=30 min). It was found that the radiation annealing provides diffusion redistribution of the impurities and a high degree of electrical activation. Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 89–92, July, 1998.     

Properties of ion implanted silicon,sulfur, and carbon in gallium arsenide

Work is described in which chromium-doped semi-insulating gallium arsenide has been successfully doped n-type with ion implanted silicon and sulfur, and p-type with ion implanted carbon. A dilute chemical etch has been employed in conjunction with differential Hall effect measurements to obtain accurate profiles of carrier concentration and mobility vs. depth in conductive implanted layers. This method has so far been applied to silicon-and sulfur-implanted layers in both Cr-doped semi-insulating GaAs and high purity vapor grown GaAs. In the case of sulfur implants, a strong diffusion enhancement has been observed during the annealing, presumably due to fast-diffusing, implantation-produced damage. Peak doping levels so far obtained are about 8 × 10¹⁷ electrons/cm³ for silicon implants and 2 × 10¹⁷ electrons/cm³ for sulfur implants. Mobility recovery has been observed to be complete except in regions near the surface which are heavily damaged by the implantation.     

Metal-insulator-semiconductor light modulators utilizing the Franz-Keldysh effect in gallium arsenide

A study was made of the electroabsorption kinetics, as well as of the spectral and field dependences of the contrast and efficiency of modulation of light in Al-SiO₂-GaAs-n⁺-GaP structures near the fundamental absorption edge of GaAs (875–910 nm). Values of the contrast amounting to 10–12 and the modulation efficiency of 30–40% were achieved. It was demonstrated that optical data storage was possible with the aid of an He-Ne laser. Optical memory was observed in Al-SiO₂-(n-n⁺-GaAs structures on application of voltage pulses causing carrier accumulation; the effect was due to the capture of electrons at the SiO₂-GaAs interface. The absorption edge of epitaxial GaAs films on GaP substrates had an exponential profile in the photon energy range 1.37h1.40 eV infields 0E 56.5·10⁴ V/cm. An empirical relationship was obtained for the spectral and field dependences of the absorption coefficient.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp.36–41, December, 1980.     

Photoquenching effect and its consequence in p type gallium arsenide

In order to examine the origin of the occasionally observed shift in the photoconductivity peak with respect to the band gap value; optical and electro-optical investigation of a p type GaAs crystal was carried out. The absorption and photochonductivity spectra were recorded and by comparing both spectra, a model based on the transition of electrons from the oxygen “adsorbate surface states” is proposed to explain the strong photoquenching observed on the high energy side of the band gap value. This also explains the observed shift.     

Hall effect and photoluminescence in vapor-phase epitaxial gallium arsenide heavily doped with sulfur

Hall mobility and photoluminescence have been studied in degenerate sulfur doped gallium arsenide vapor-epitaxial films. The results are in agreement with the measurements on tellurium and selenium doped GaAs made earlier by several investigators.     

Long-range structural interaction effect in gallium arsenide during ion bombardment

Transmission electron microscopy is used to study changes in the structure of gallium arsenide samples after bombardment by high doses of 5 keV argon ions. A change in the structure of the samples is observed at depths exceeding the average penetration depth of the ions by an order of magnitude. A model is proposed to explain the long-range structural interaction effect in gallium arsenide in terms of a phase transition induced by elastic stresses in the sample. Fiz. Tverd. Tela (St. Petersburg) 40, 438–440 (March 1998)     

Ferromagnetism in epitaxial layers of gallium and indium antimonides and indium arsenide supersaturated by manganese impurity

We report on laser synthesis of thin 30–200 nm epitaxial layers with mosaic structure of diluted magnetic semiconductors GaSb:Mn and InSb:Mn with the Curie temperature T_C above 500 K and of InAs:Mn with T_C no less than 77 K. The concentration of Mn was ranged from 0.02 to 0.15. In the case of InSb:Mn and InAs:Mn films, the additional pulse laser annealing was needed to achieve ferromagnetic behavior. We used Kerr and Hall effects methods as well as ferromagnetic resonance (FMR) spectroscopy to study magnetic properties of the samples. The anisotropy FMR was observed for both layers of GaSb:Mn and InSb:Mn up to 500 K but it takes place with different temperature dependencies of absorption spectra peaks. The resonance field value and amplitude of FMR signal on the temperature is monotonically decreased with the temperature increase for InSb:Mn. In the case of GaSb:Mn, this dependence is not monotonic.     

Formation of a system of InGaAs quantum wires in a gallium arsenide matrix

The formation of a system of one-dimensional quantum conductors in porous multilayer In_xGa_1?xAs/GaAs structures with a two-dimensional charge-carrier gas in the In_xGa_1?xAs layers is discussed. The transition from the single-crystalline to porous matrix is studied with scanning atomic force microcopy. A decrease in the dimensionality of the electron-hole gas in the objects, i.e., a transition from the two-dimensional to a one-dimensional system, is established by analyzing the dependences of the position and width of a spectral line in the photoluminescence spectra on the etching time. Both multilayer periodic superlattices and a structure with a single In_xGa_1?xAs layer located near the surface of gallium arsenide are studied. The electrophysical characteristics of electrons in the porous superlattices are measured as functions of temperature. They confirm the formation of a new structure and indicate a change in the mechanism of electron scattering in the quasi-one-dimensional transport channels formed in the system.     

半绝缘砷化镓单晶中碳微区分布的研究

通过AB腐蚀（由Abrahams和Buiocchi发明的腐蚀方法，简称AB腐蚀）、KOH腐蚀，经金相显微镜观察、透射电子显微镜能谱分析、电子探针x射线微区分析，对液封直拉法生长的非掺 半绝缘砷化镓单晶中碳的微区分布进行了分析研究.实验结果表明，碳的微区分布受单晶中 高密度位错网络结构的影响.高密度位错区，位错形成较小的胞状结构，且胞内不存在孤立 位错，碳在单个胞内呈U型分布；较低密度位错区，胞状结构直径较大，且胞内存在孤立位 错，碳在单个胞内呈W型分布. 关键词： 半绝缘砷化镓 胞状位错 碳受主