注硅半绝缘GaAs的深能级

用深能级瞬态谱(DLTS)详细研究了硅离子注入Liquid-encapsulated Czochralski(缩写为LEC)半绝缘GaAs的深中心。结果表明,在注硅并经高温退火的有源区中观测到4个多子(电子)陷阱,E₀₁,E₀₂,E₀₃和E₀₄。它们的电子表观激活能分别为0.298,0.341,0.555和0.821eV。其中E₀₄与EL2有关,但不是EL2缺陷。E₀₄的电子 关键词：     

Features of OSL and TL properties of anion-defective corundum crystals exposed to thermo-optical treatment

The results of systematic investigation of the mechanisms and role of phototransfer in TL and OSL processes in α-Al₂O_3−δ crystals under controlled filling of the main and deep traps depleted at 450 and 720 K, respectively, are presented.Optical depletion spectra of the main and deep traps were measured and compared. It was found that green light stimulation only depletes the main trap, while blue light depletes both the main and deep traps. Optical depletion of the deep trap results in phototransfer of charges that can be realized by 2 mechanisms: either through the main trap to recombination centers or directly to the latter. However, the dominant contribution to the OSL signal is provided by phototransfer through the main trap. It is also found that UV emission at 3.7 eV dominates over F-emission at 3.0 eV in the phototransferred TL spectrum. It is assumed that this UV emission is not related to the F⁺ centers.     

Short-lived primary radiation defects in LiF crystals

The spectral and kinetic parameters of electron-pulse-initiated transient absorption and emission of LiF crystals were studied using pulsed spectrometry with a nanosecond time resolution. The measurements were performed in the spectral region of 6 eV, the temperature range of 11–150 K, and within 10^?8–10 s after the termination of an electron pulse. It is shown that the electron-pulse irradiation not only gives rise to F, V _k , and H centers in the LiF crystal but also to certain short-lived defects of two types that differ in the spectral positions of the absorptive and radiative transitions, the lifetime, and the temperature dependence of the production efficiency. Defects of type I feature absorptive transitions at 5.5 and 5.1 eV and a radiative transition at 5.8 eV, whereas the absorptive transitions at 5.3 and 4.75 eV and a radiative transition at 4.4 eV are characteristic of type-II defects. It is found that a variation in the ratio between the concentrations of the different types of short-lived centers in the range of 11–150 K does not affect the quantum efficiency of the F centers. It is assumed that the observed centers are self-trapped excitons of various types.     

A study of deformation-produced deep levels inn-GaAs using deep level transient capacitance spectroscopy

Deformation-produced deep levels, both of electron and hole traps, have been studied using deep level transient capacitance spectroscopy (DLTS) for an undopedn-type GaAs (HB grown) compressed at 440°C. Concentrations of two grown-in electron trap levels (E _c −0.65eV andE _c −0.74eV) and one grown-in hole trap level (E _v +∼0.4eV) increase with plastic deformation, while that of a grown-in electron trap level (E _c −∼0.3eV) decreases in an early stage of deformation. While no new peak appeared in the electron trap DLTS spectrum after plastic deformation, in the hole trap DLTS spectrum a broad spectrum, seemingly composed of many peaks, newly appeared in a middle temperature range, which may be attributed to electronic energy levels of dislocations with various characters.     

Determination of deep electron traps in GaAs by time-resolved capacitance measurement

A useful technique of determining the energy levels and the spatial density distributions of multiple electron traps in semi-conductor has been developed using the time-resolved measurement of the Schottky barrier junction capacitance, and this technique has been applied to characterize the electron traps inn-GaAs. In the present technique, the energy levels are determined from single scan of temperature, and the density distributions are calculated from a set of capacitance-voltage relationships. Four traps which lay at 0.39, 0.73, 0.79, and 0.58 eV below the conduction band edge were observed in boat grown or vapor phase epitaxially grown crystals. Many layers which were obtained by a vapor phase epitaxial growth system with N₂ carrier gas were measured and it was found that almost all of them include the 0.73 eV and the 0.79 eV trap with the density between 1×10¹³ and 2×10¹⁵ cm⁻³.     

Formation of defects in gallium phosphide grown in the presence of oxygen

The influence of oxygen introduced in the gaseous phase on the formation of defects in GaP epitaxial layers is investigated by deep-level transient spectroscopy. The extremal dependences of the concentrations of charge carriers and electron traps with energy E _c−0.24 eV on the oxygen flux are discussed. Zh. Tekh. Fiz. 67, 52–55 (September 1997)     

Effect of alpha-particle irradiation on the electrical properties of n-type Ge

Deep-level transient spectroscopy was used to investigate the effect of alpha particle irradiation on the electrical properties of n-type Ge. The samples were irradiated with alpha particles at room temperature using an americium-241 (Am-241) radionuclide source. The main defects introduced were found to be electron traps with energy levels at E_C−0.38, E_C−0.21, E_C−0.20, E_C−0.15, and E_C−0.10 eV, respectively. The main defects in alpha particle irradiation are similar to those introduced by MeV electron irradiation, where the main defect is the E-center. A quadratic increase in concentration as a function of dose is observed.     

Electron and hole injection in metal-oxide-nitride-oxide-silicon structures

The kinetics of electron and hole accumulation in metal-oxide-nitride-oxide-semiconductor structures is studied. Experimental data are compared with a theoretical model that takes into account tunnel injection, electron and hole capture by traps in amorphous silicon nitride SiN_x, and trap ionization. Agreement between experimental and calculated data is obtained for the bandgap width E _g = 8.0 eV of amorphous SiO₂, which corresponds to the barrier for holes Φ_h = 3.8 eV at the Si/SiO₂ interface. The tunneling effective masses for holes in SiO₂ and SiN_x are estimated at m _h ^* ≈ (0.4–0.5)m ₀. The parameters of electron and hole traps in SiN_x are determined within the phonon-coupled trap model: the optical energy W _opt = 2.6 eV and the thermal energy W _T = 1.3 eV.     

Deep level structure and compensation mechanism in In-doped CdTe crystals

Deep Level Transient Spectroscopy (DLTS) and Optical Deep Level Transient Spectroscopy (ODLTS) experiments have been conducted on a series of In-doped CdTe crystals grown by the Bridgman or the travelling heater (THM) methods using Te as the solvent. The THM samples are n-type but strongly compensated. Annealing at 700°C under high Cd vapour pressure leads to a decompensation of the crystals. The electron concentration is then a measure of the donor (In) concentration, which was in the range 3 × 10¹⁶−1.5 × 10¹⁸cm⁻³. Six and eight electron traps are, respectively detected in the non-annealed and annealed samples at a concentration level 10²–10³ times below the net electron concentration. They cover the energy range 0.2–0.8 eV. Similar traps are found in both types of crystals, the concentration of which increases with In content and after annealing. The presence of In interstitial-type defects is suggested. A main hole trap at 0.12eV is detected by ODLTS in compensated samples with a concentration close to the donor concentration. Low temperature electrical measurements show that this trap is ionized under equilibrium conditions. It appears to be the main compensating acceptor centre. A plausible microscopic structure is In_cdV_cd. This study shows that In-doped CdTe grown by THM is electrically compensated and that In-containing neutral associates or precipitates play a minor role in the compensation mechanism.     

Characteristics of traps in TlInS2 single crystals

Characteristics of charge traps in TlInS₂ single crystals are investigated by the use of thermally stimulated current (TSC) technique. The TSC spectra of the sample from 80 K to 300 K are recorded at a constant heating rate. The spectra reveal that there are several trapping levels associated with the complex structure of overlapping peaks. The experimental results indicate that the traps in TlInS₂ associated with the spectra in the measuring range of temperature obey the monomolecular (first order) kinetics. Thus, the spectra are resolved into first order shaped peaks by the use of computerized best fit procedure. The trapping parameters; such as the energy depth, temperature dependent frequency factor and capture cross section, together with concentrations of the corresponding six discrete levels are computed. These centers all having low capture cross sections with strong temperature dependence are found to be at the energies of 0.11 eV, 0.22 eV, 0.25 eV, 0.26 eV, 0.29 eV and 0.30 eV with high concentrations of 6.6 × 10¹⁶, 2.0 × 10¹⁷, 3.3 × 10¹⁷, 9.6 × 10¹⁶, 2.3 × 10¹⁷ and 4.0 × 10¹⁷ cm^?3, respectively.     

Photoinjection phenomena in a silicon-silcon dioxide system

Silicon-silicon dioxide structures obtained by thermal, anodic, and chemical oxidation of silicon are studied by the photocharge and photoinjection current methods. It is shown that the extent of the fluctuation state tails" near the edges of the SiO₂ forbidden zone is small (0.2 eV). The threshold for negative photocharging of anodic oxide traps is found to decrease with increase in oxide thickness, a fact related to the existence of a nonstoichiometric transition layer between the silicon and silicon dioxide. The effect of hydration and dehydration on negative optical charge of oxide traps is studied, and it is shown that the basis of electron traps is formed by the most hydrated and deformed SiO₄H_n tetrahedra. The possibility of creating electron and hole traps in the oxide layer by doping with metal ions from a solution is demonstrated. It is found that the corresponding defects are also adsorption centers for water molecules by a coordination mechanism.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 3–7, July, 1981.In conclusion, the authors thank V. F. Kiselev for his interest in the study and valuable remarks.     

双异质结AlxGa1-xAs/GaAs发光管中与氧有关能级的测量

用DLTS和单次脉冲瞬态电容技术研究了液相外延生长的双异质结AlxGa1-xAs/GaAs发光管,掺Si的n-Al0.05Ga0.95As有源层中的深能级。着重分析了一个与氧有关的电子陷阱,其发射激活能为EC-ED=0.29eV。我们发现该电子陷阱随正向注入脉冲宽度tp的增加DLTS峰向低温移动,即在确定的温度下发射率随tp的增加而增加。用DLTS首次测得该能级的俘获瞬态谱,发现俘获峰随反向撤空脉冲宽度tR的增加向低温端移动,即在确定的温度下俘获率随tR的增加而增加,并且俘获激活能从△Eσ=0.28eV变化到0.26eV,用位形坐标图讨论了引起变化的原因。     

Ionoluminescence in the presence of ionizing radiation

An increase in the ionoluminescence intensity from a ZnS-CdS:Ag sample by a factor of more than 20 upon additional electronic excitation by UV light has been found. The effect decreases in magnitude with an increase in the energy of bombarding H₂⁺ ions and peaks at an energy below 175 eV. This effect manifests itself in samples having a system of shallow electron traps and is due to the relaxation of highly excited anharmonic atomic vibrations, caused by the ion impact, through the electronic channel. A mechanism is proposed and computed for the phenomenon revealed.     

Basic thermoluminescent and dosimetric properties of Al2O3:C irradiated by pulse intensive electron beam

The effect of deep traps filled by a pulse electron beam on the thermoluminescent (TL) properties in Al₂O₃:C dosimetric crystals is studied. When the deep traps are filled, the dosimetric peak at 170 °C acquires a double-peak structure not present in the initial samples. The effect of the population of the deep centers having various nature (electron or hole traps) and energy depth on the shape of the dosimetric TL peak structure is analyzed. An assumption is made that in the temperature ranges of 350–500 °C and 650–750 °C, electron traps are emptied, whereas at T = 500–650 °C hole traps are emptied. The possibility of using the TL associated with deep traps in high-dose dosimetry of pulse electron beams is shown.     

Influence of an electric field on photostimulated states in NH4BPh4 films

The influence of an electric field on stable photostimulated triplet states of NH₄BPh₄ at a temperature of 77 K have been studied by EPR spectroscopy. It has been established that, on exposure to UV radiation, electron capture by traps in the band gaps takes place with formation of triplet state. After application of an electric field, triplet states are destructed because, with an increase in the applied voltage, a gradual inclination of energy bands takes place and electrons found in traps on different energy levels are released. The assumption that captured electrons are found in traps on different energy levels is confirmed by earlier studies of thermoluminescence spectra.     

分子束外延生长的n型Al掺杂ZnS1-xTex深中心研究

应用电容-电压、光致荧光和深能级瞬态谱技术研究了分子束外延生长的n型Al掺杂ZnS_1-xTe_x外延层深中心.Al掺杂ZnS_0.977Te_0.023的光致荧光强度明显低于不掺杂的ZnS_0.977Te_0.023，这表明一部分Al原子形成非辐射深中心.Al掺杂ZnS_1-xTe_x(x=0，0.017，0.04和0.046)的深能级瞬态傅里叶 关键词：     

Thermally stimulated current and high temperature resistivity measurements of 4H semi-insulating silicon carbide

High purity semi-insulating 4H SiC single crystals have potential applications for room temperature radiation detectors because of the wide band gap and radiation hardness. To control carrier lifetime, a key parameter for high performance radiation detectors, it is important to understand the nature of the deep traps in this material. For this purpose, we have successfully applied thermally stimulated current (TSC) and high temperature resistivity measurements to investigate deep level centers in semi-insulating 4H SiC samples grown by physical vapor transport. High temperature resistivity measurements showed that the resistivity at elevated temperatures is controlled by the deep level with an activation energy of 1.56 eV. The dominant traps revealed by TSC measurements were at 1.1-1.2 eV. The deep trap levels in 4H-SiC samples, the impurity and point defect nature of TSC traps peaked at ∼106 K (0.23 eV), ∼126 K (0.32 eV), ∼370 K (0.95 eV), ∼456 K (1.1-1.2 eV) are discussed.     

Deep level transient spectroscopy (DLTS) study of defects introduced in antimony doped Ge by 2 MeV proton irradiation

Deep level transient spectroscopy (DLTS) and Laplace-DLTS have been used to investigate the defects created in Sb doped Ge after irradiation with 2 MeV protons having a fluence of 1×10¹³ protons/cm². The results show that proton irradiation resulted in primary hole traps at E_V +0.15 and E_V +0.30 eV and electron traps at E_C ?0.38, E_C ?0.32, E_C ?0.31, E_C ?0.22, E_C ?0.20, E_C ?0.17, E_C ?0.15 and E_C ?0.04 eV. Defects observed in this study are compared with those introduced in similar samples after MeV electron irradiation reported earlier. E_C ?0.31, E_C ?0.17 and E_C ?0.04, and E_V +0.15 eV were not observed previously in similar samples after high energy irradiation. Results from this study suggest that although similar defects are introduced by electron and proton irradiation, traps introduced by the latter are dose dependent.     

Fast electron energy loss spectrum of an amorphous tungsten trioxide film

The forward scattering energy loss spectrum of 300 KeV electrons transmitted through thin films of WO₃ has been measured in the energy range of 0.8–225 eV with an energy loss resolution of 0.1 eV. Energy losses due to excitation of color centers, inter band transitions and core elestrons in WO₃ have been identified. Measurement of the elastic electron difraction pattern revealed the amorphous nature of the film with structural differences depending upon the preparative methods.     

电子辐照硅层中缺陷能级的研究

用12MeV电子辐照硅p⁺n结,在硅中除引入氧空位E₁(E_c-0.19eV),双空位E₂(E_c-0.24eV)和E₄(E_c-0.44eV)外,还引入缺陷E₃(E_c-0.37eV)。用DLTS方法和反向恢复时间测量研究了这些能级的退火行为,可以看到,E₃的退火温度最高(≈520℃)。由退火特 关键词：