Electrophysical properties and annealing of defects in nuclear transmutation-doped GaAs irradiated by H+ ions

A study has been made of the electrophysical characteristics of nuclear-transmutation-doped GaAs (NTDG) and GaAs doped with metallurgical impurities Sn, Te, Ge, and In, after irradiation by H⁺ ions at fluxes of up to 1.5·10¹⁶ cm^–2. It is shown that the changes in the GaAs produced by irradiation do not depend on the method used to dope the material and can be described on the basis of the known spectrum of E and H traps in GaAs. Crystals of GaAs annealed after irradiation display deep (P1–P3) traps, which are responsible for the high-temperature proton insulation GaAs.V. D. Kuznetsov Siberian Physicotechnical Institute at the State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 61–65, October, 1992.     

Specific Features of the Photoconductivity of Compensated i-GaAs in the Spectral Range with hν > E g

The photoconductivity of semi-insulating GaAs compensated by chromium oxide is investigated. It is demonstrated that after heat treatment, the current photosensitivity of a sample irradiated with particles whose energies exceed the band gap reaches large values, which does not agree with the De Vore theory. These large photosensitivity values are due to slowing down of the surface recombination caused by the presence of oxygen in i-GaAs. The high current photosensitivity extends to = 0.52 m. The observed structure of the photoconductivity spectrum is most likely caused by vertical electron transitions from the valence subband, split in the process of spin-orbital interaction, to the central minimum of the conduction band. The influence of crystal irradiation by particles with energies h > E _g on the spectral photoconductivity distribution is investigated. It is demonstrated that irradiation by electrons and -quanta causes the photocurrent to increase. After neutron irradiation, the photocurrent decreases at short wavelengths in accordance with the De Vore theory. It is demonstrated that i-GaAs 2O₃> is a very sensitive detector of red radiation.     

Some photoelectric properties of p-GaSe monocrystals

The thermostimulated conductivity, static characteristics, and kinetics of photoconductivity in undoped GaSe monocrystals with p-type conductivity are studied over the temperature range 80–350K. Photocurrent as a function of intensity and wavelength of exciting light, and relaxation curves are analyzed. Insignificant temperature and infrared photocurrent extinction was observed. The major parameters of photosensitive centers are determined. It is demonstrated that the experimentally observed principles of photoconductivity in gallium selenide can be explained within the framework of the two-center recombination model, as realized for many wide-zone photoconductors [1–3].Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 66–70, January, 1976.     

Electrical, optical, and photoelectric properties of electron-irradiated indium-doped cadmium sulfide single crystals

The effect of irradiation by 1.2-MeV electrons to a dose Φ=2×10¹⁷ cm^?2 on the electrical, optical, and photoelectric properties of In-doped CdS single crystals was studied. The experimental data obtained permit one to conclude that irradiation initiates decomposition of the supersaturated In solution in CdS, with the indium atoms at the sites of the cation sublattice being expelled by cadmium interstitial atoms. New slow-recombination centers were observed to exist in the irradiated CdS: In samples, with the maxima of optical quenching of the photoconductivity lying in the region of $\lambda _{M_1 } = 0.75\mu m$ and $\lambda _{M_2 } = 1.03\mu m$ . It is suggested that the new recombination centers are related to complexes containing cadmium vacancies and indium atoms.     

Study on irradiation-induced defects in GaAs/AlGaAs core–shell nanowires via photoluminescence technique

To gain a physical insight into the radiation effect on nanowires(NWs), the time resolved photoluminescence(TRPL)technique is used to investigate the carrier dynamic behaviors in GaAs/AlGaAs core–shell NWs before and after 1-MeV proton irradiation with fluences ranging from 1.0 × 10~(12) cm~(-2) to 3.0 × 10~(13) cm~(-2). It is found that the degradations of spectral peak intensity and minority carrier lifetime show similar trends against irradiation fluence, which is closely related to the displacement defects induced by irradiation. We also find that the proton irradiation-induced defects behave as Shockley–Read–Hall(SRH) recombination center trapping free carriers. Finally, the defect concentration could be estimated through measuring the minority carrier lifetime.     

Photostimulation of photoconductivity in electron-irradiated CdS:Cu single crystals

We have studied the photoconductivity of CdS:Cu single crystals irradiated by fast electrons. When the density of fast recombination centers (s-centers) due to the electron irradiation is high, one observes photostimulation of photoconductivity (PSP). PSP is due to the photoexcitation of holes from the s-centers into the valence band and their subsequent decay at slow recombination centers. The energy location of the s-centers can be found from the peak in the PSP spectrum; we find that E_s=E_v+(1.67 ± 0.02) eV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 50–53, January, 1989.     

Investigation of intrinsic defect-related deep centers in ZnSe

We have studied deep centers in highly resistive ( 10¹² ·cm) ZnSe, containing intrinsic impurities and defects, by means of nonequilibrium photoconductivity, photoluminescence, and wavelength-modulated transmission spectroscopy. We have determined the energy positions of photosensitive deep acceptors with ionization energies of 0.10, 0.18, 0.23, 0.27, 0.34, and 0.47 eV, as well as of radiative and nonradiative recombination centers.ted from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 42–46, March, 1989.The authors consider it a pleasant duty to thank M. K. Sheinkman for his interest in This work and S. S. Ostapenko for his help in PL measurements and helpful discussions.     

Rearrangement of defects in single crystals of cadmium sulfide irradiated with fast electrons

This study exaines CdS single crystals subjected to a special nonalloying treatment, alloyed with copper, and annealed in a cadmium atmosphere. Irradiation of the test specimens by electrons with E 1.2 MeV led to the formation of mobile defects and to decomposition of the original donor-acceptor associates. Over time, the primary radiation defects form secondary defects which act as fast recombination centers responsible for impurity photoconductivity. New donor-acceptor pairs are formed when the irradiated specimens are stored, these pairs being paramagnetic centers. Conclusions are made as to the nature of the secondary radiation defects, which are distributed both in the body of the specimens and near their surface.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 5–9, May, 1988.     

Fir spectroscopy on shallow donor states in GaAs:Si

Far infrared spectroscopy experiments on the shallow donor states of GaAs:Si are presented. Transitions between shallow donor levels are induced by F.I.R. radiation from an optically pumped molecular gas laser. The measurements are performed by measuring the electrical conductivity of the GaAs:Si sample at fixed laser frequencies by sweeping an external applied magnetic field up to 12 T. In total about 30 different transitions are observed using radiation between 60 m and 1.8 mm. In low magnetic fields and at high frequencies a series of photoconductivity signals are observed, which we ascribe to transitions from the ground state towards bound donor levels with hydrogen quantum numbers n, l=n–1, and m=n–1.     

GaInP/GaAs/Ge三结太阳电池不同能量质子辐照损伤模拟

以GaInP/GaAs/Ge三结太阳电池为研究对象,开展了能量为0.7, 1, 3, 5, 10 MeV的质子辐照损伤模拟研究,建立了三结太阳电池结构模型和不同能量质子辐照模型,获得了不同质子辐照条件下的I-V曲线,光谱响应曲线,结合已有实验结果验证了本文模拟结果,分析了三结太阳电池短路电流、开路电压、最大功率、光谱响应随质子能量的变化规律,利用不同辐照条件下三结太阳电池最大输出功率退化结果,拟合得到了三结太阳电池最大输出功率随位移损伤剂量的退化曲线.研究结果表明,质子辐照会在三结太阳电池中引入位移损伤缺陷,使得少数载流子扩散长度退化幅度随质子能量的减小而增大,从而导致三结太阳电池相关电学参数的退化随质子能量的减小而增大.相同辐照条件下,中电池光谱响应退化幅度远大于顶电池光谱响应退化幅度,中电池抗辐照性能较差,同时中电池长波范围内光谱响应的退化幅度比短波范围更大,表明中电池相关电学参数的退化主要来源于基区损伤.     

170 keV Proton radiation effects on low-frequency noise of bipolar junction transistors

In this paper, the electrical properties and low-frequency noise for bipolar junction transistors irradiated by 170?keV proton are examined. The result indicates that for the sample under proton irradiation with fluence 1.25?×?10^14?p/cm², base current I_B in low bias range (V_BE < 0.7?V) increases due to superimposition of radiation-induced recombination current, while the gain decreases significantly. Meanwhile, the low-frequency noise increases in the proton-irradiated sample. By analysis of evolution of parameters extracted from low-frequency noise power spectra, it is demonstrated that radiation-induced noise is mainly originated from carrier fluctuation modulated by generation–recombination centers (G–R centers) located at the interface of Si/SiO₂, which are introduced by proton-radiation-induced defects. It is also confirmed that the electrical properties and noise behavior of irradiated sample are mostly affected by the carrier recombination process caused by G–R centers at the interface of Si/SiO₂ than by G–R centers in EB junctions.     

100 keV质子辐照对空间GaAs/Ge太阳电池光电效应的影响

利用空间环境模拟设备,用固定能量为100keV、注量为1×10⁹—3×10¹²cm^-2的质子,对空间实用GaAs/Ge太阳电池进行了辐照试验.利用伏安(I-V)特性、光谱响应和光致发光(PL)光谱测试,研究分析了电池的光电效应.试验表明,电池的各种电性能参数如短路电流(I_sc)、开路电压(V_oc)、最大输出功率(P_{m< 关键词： GaAs/Ge太阳电池 质子辐照 光电效应}     

Resonant tunneling of electrons through virtual interference states formed as a result of reflection from the boundary of strongly doped region of GaAs

The paper is devoted to analysis of the electron transport through one-barrier GaAs/AlAs/GaAs heterostructures. The oscillating component of transport characteristics of symmetric one-barrier GaAs/AlAs/GaAs heterostructures with spacers, which is associated with resonance tunneling of electrons via virtual states formed in the spacer region of the structures due to reflection of electrons from the n^?-GaAs/n⁺-GaAs interface and their subsequent interference. It is shown that electrons are predominantly reflected coherently from the boundary of the strongly doped region as in the case of one-dimensional averaged potential of randomly arranged (beginning from this boundary) impurities. It is shown that low-energy virtual resonances are suppressed due to electron scattering as a result of their interaction with longitudinal optical (LO) phonons in the spacer region.     

质子辐射损伤对单结GaAs/Ge太阳电池暗特性参数的影响

基于p-n结暗特性双指数模型,对经质子辐射后的单结GaAs/Ge太阳电池的暗特性I-V曲线进行数值拟合,确定了单结GaAs/Ge太阳电池在辐射前后的四个暗特性特征参数,即串联电阻R_s、并联电阻R_(sh)、扩散电流I_(s1)和复合电流I_(s2).研究结果表明,质子辐射后单结GaAs/Ge太阳电池的R_s,R_(sh),I_(s1)和I_(s2)四个暗特性参数均发生显著变化.经低能质子辐射后,单结GaAs/Ge太阳电池的R_(sh)随位移损伤剂量的增加而减小,而R_s,I_(s1)和I_(s2)三个参数随位移损伤剂量的增加而增大,其中串联电阻随位移损伤剂量线性增加而与辐射质子能量无关.理论分析表明,上述参数的变化与质子辐射损伤区域分布有关.基区和发射区的损伤主要引起单结电池串联电阻和扩散电流的增加;结区的损伤导致并联电阻减小,复合电流增大.     

Recombination of nonequilibrium current carriers in n-InAs1−x−ySbxPy

The stationary photoconductivity, the photomagnetic effect, and the relaxation kinetics of photoconductivity in n-InAs_1–x–ySb_xP_y crystals (x=0.06, y=0.11) with n₀ = 8·10¹⁵ and 3·10¹⁶ cm^–3 were measured and the lifetimes of nonequilibrium current carriers in the temperature interval T=78–295 K were determined. The possible mechanisms of recombination, which limit the lifetimes (radiative _R, Auger recombination _A, and recombination through centers with E_f=0.13 eV), which, as is demonstrated, are determined by interband recombination processes with _RA = _RA/(_R + _A), are calculated theoretically. The contribution of the 0.13 eV recombination centers can be significant when n₀10¹⁴ cm^–3.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 52–54, April, 1991.     

Investigation on trap distribution and photoelectronic effect due to UV,IR and visible light excitation in self-activated zns crystals

Photoelectronic effects in IR sensitive ZnS crystals are found for IR, UV and visible light excitations. The transient rise characteristic of UV excited photoluminescence (UPL) saturates faster than UV produced photoconductivity (UPC). The UPC shows a typical S-shaped rise curve for any 365 run excitation irradiance and temperature. Simultaneously measured transient behaviors of IR induced photoconductivity (INP) and IR stimulated luminescence (STL) have a strong IR excitation intensity dependence for λ_IR = 2.5?4.6 microm. A unique phenomenon, quick rise followed by quick decay during the initial 20 msec, is found in INP before reaching final maximum but is not observed in STL. During UV steady irradiation, additional photoconductivity and luminescence are quickly induced by an abrupt IR excitation of 2.5 microm. Then, the photoconductivity reaches a new steady state level below UPC steady state. However, the luminescence sets the same UPL steady state level. This means that photoconductivity exhibits an IR optical quenching but not stimulation, while neither optical quenching nor stimulation is found in luminescence. It is also possible to quench the UPC response with visible light excitation at 570 nm. These observations support the previously reported discussion that IR absorbing impurity centers and shallow traps, including recombination (or luminescence) centers must be involved in IR stimulable ZnS crystals. They also indicate the presence of deep trap centers for E_T ≈ 2.18 eV, which have a strong role in slow UPC rise.     

Nonsteady photoconductivity of layers of glass of the As-Se system

This article examines experimental results from a study of impulsive photoconductivity in layers of glasses of As_xSe_100–x (30-@#@ 60). It was found that thermal and laser treatment (thermo- and photostructural changes) affect the character of relaxation processes in photoconduction in freshly prepared layers. It was also established that both annealing at temperatures near the softening point of the glass and laser irradiation with quantum energies exceeding the width of the forbidden band are accompanied by a change in the recombination lifetime of nonequilibrium carriers. It is concluded on the basis of empirical data that an efficient recombination channel complementary to the main channel (tunnel transition of the type 2D⁰D⁺+D^–) is present in freshly prepared layers. The latter is present in annealed layers. The additional recombination channel is related to the existence of homopolar bonds in binary arsenic selenides and is proven to exist by data on the effect of composition on photocurrent relaxation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 66–71, May, 1987.     

Optical charge transfer for the dope in GaAs<Cr>

It is concluded that the chromium dope is amphoteric in behavior on the basis of the spectra, kinetics, and lux-ampere characteristics of the absorption and photoconductivity induced by 1.15-μm IR laser radiation in high-resistance specimens of GaAs〈Cr〉. It is assumed that the additional IR illumination produces optical charge transfer in the chromium in accordance with Cr³⁺3d³ + hν → Cr²⁺3d⁴ + Cr⁴⁺3d². The photoneutralization of the Cr⁴⁺3d² centers is responsible for additional optical-absorption and photoconductivity bands appearing in the long-wave region. The kinetic equations for these centers are solved, which describes the experimental results satisfactorily. It is suggested that chromium may compensate not only shallow donors in GaAs but also shallow acceptors.     

Low temperature thermal properties of crystalline quartz after electron irradiation

Measurements of the temperature specific heat (between 0.12K and 8K) and thermal conductivity (between 0.5K and 20K) of crystalline -quartz after electron irradiation are reported. In the temperature region below 1K the specific heat is larger than in the unirradiated sample. This can be attributed to low energy excitations which are created during irradiation and which are associated with Al impurities. The thermal conductivity is reduced after irradiation. Below 4K the additional thermal resistivity varies asT ^–1.5. The phonon scattering by radiation-induced excitations in -quartz is weak compared to phonon scattering by two level systems (TLS) in vitreous silica.     

Electrical and luminescent properties of gallium phosphide with radiation defects

The energy spectrum of local levels and the effect of radiation damage on intensity and character of cathode luminescence lines in the visible region of the spectrum in gallium phosphide single crystals prepared from a solution-melt by the Chochralski method are examined. It is shown that as a result of irradiation by fast electrons with E_e=1 Mev and Co 60 -quanta, both donor and acceptor centers are introduced into the original crystals. New radiation centers producing lines in the spectral range studied (500–600 nm) were not observed after irradiation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 49–54, June, 1976.