共查询到20条相似文献,搜索用时 156 毫秒
1.
B. G. Tagiev U. F. Kasumov N. N. Musaeva R. B. Dzhabbarov 《Physics of the Solid State》2003,45(3):426-432
The current-voltage characteristics of Ca4Ga2S7: Eu3+ single crystals are measured for the first time, and the processes affecting these characteristics are analyzed theoretically. It is demonstrated that Ca4Ga2S7: Eu3+ single crystals are high-resistance semiconductors with a resistivity of ~109 Ω cm and a relative permittivity of 10.55. The electrical properties of the studied materials are governed by traps with activation energies of 0.13 and 0.19 eV and a density ranging from 9.5×1014 to 2.7×1015 cm?3. The one-carrier injection is observed in weak electric fields. In electric fields with a strength of more than 4×103 V/cm, traps undergo thermal field ionization according to the Pool-Frenkel mechanism. At low temperatures and strong fields (160 K and 5×104 V/cm), the electric current is most likely due to hopping conduction by charge carriers over local levels in the band gap in the vicinity of the Fermi level. 相似文献
2.
D. Ghosh B. Ghosh S. Hussain R. Bhar A. K. Pal 《Applied Physics A: Materials Science & Processing》2014,115(4):1251-1261
Gallium antimonide (GaSb) films were deposited onto fused silica and n-Si (100) substrates by coevaporating Ga and Sb from appropriate evaporation sources. The films were polycrystalline in nature. The size and the shape of the grains varied with the change in the substrate temperature during deposition. The average surface roughness of the films was estimated to be 10 nm. Grain boundary trap states varied between 2×1012 and 2.2×1012 cm?2 while barrier height at the grain boundaries varied between 0.09 eV and 0.10 eV for films deposited at higher temperatures. Stress in the films decreased for films deposited at higher temperatures. XPS studies indicated two strong peaks located at ~543 eV and ~1121 eV for Sb 3d3/2 and Ga 2p3/2 core-level spectra, respectively. The PL spectra measured at 300 K was dominated by a strong peak located ~0.55 eV followed by two low intensity peaks ~0.63 eV and 0.67 eV. A typical n-Si/GaSb photovoltaic cell fabricated here indicated V oc~311 mV and J~29.45 mA/cm2, the density of donors (N d)~3.87×1015 cm?3, built in potential (V bi)~0.48 V and carrier life time (τ)~28.5 ms. Impedance spectroscopy measurements indicated a dielectric relaxation time ~100 μs. 相似文献
3.
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Two new DLTS bands I and II have been observed in n-type germanium containing 1016 cm-3 interstitial oxygen. The signature of II is: Ec?EII = 0.031 eV, K = 4 × 107 cm?2s?1; level I is about half as deep. In addision, the excitation spectrum of I is recorded by PTIS. It is composed of three hydrogenic donor series Ia, b, c with activation energies 17.25, 17.6 and 18.1 meV. The donors I and II are thought to correspond with the well known thermal oxygen donors. Energies for the latter were determined at 0.017 and 0.04 eV from Hall effect by Fuller and Doleiden. The possibility of double donors is examined, in analogy with the case of oxygen donors in silicon. 相似文献
5.
V. S. Krivobok I. A. Denisov E. N. Mozhevitina S. N. Nikolaev E. E. Onishchenko A. A. Pruchkina A. A. Silina N. A. Smirnova M. A. Chernopitsskii N. I. Shmatov 《Physics of the Solid State》2016,58(5):981-991
Shallow impurity–defect states in undoped Cd1–xZnxTe (x ~ 3–6%) single crystals have been studied using low-temperature photoluminescence measurements. It has been found that the effect exerted by zinc is mainly reduced to a rigid shift of all the specific features associated with the exciton radiation, which made it possible, with a high (~0.3 meV) accuracy, to measure the band gap and the zinc concentration in solid solutions. Hydrogen-like donors with the ground-state energy of ~14 meV and four types of acceptors with average activation energies of 59.3 ± 0.6 meV, 69.6 ± 1.5 meV, 155.8 ± 2.0 meV, and 52.3 ± 0.6 meV have been identified in all the crystals studied. Based on a comparison with the results of the analysis of the impurity background and the data available in the literature on impurity–defect emission in undoped CdTe, the first three acceptors can be assigned to the substitutional impurities NaCd, PTe, and CuCd, respectively. The most shallow acceptor (52.3 ± 0.6 meV) is a complex defect in which there is a nonstandard excited level separated by only 7 meV from the ground level. This level is formed apparently due to the removal of degeneracy, which is characteristic of TD acceptors, by the low-symmetry potential of the complex defect. 相似文献
6.
H.R. Vydyanath S.S. Chern F.A. Kroger 《Journal of Physics and Chemistry of Solids》1973,34(8):1317-1321
Iodine doped single crystals of CdS were grown from the vapor phase. High temperature Hall effect measurements for the crystals equilibrated with Cd and S2 vapors at temperatures between 700 and 1000°C gave the free electron concentration as a function of pCd or pS2 and temperature. The results can be explained on the basis of a model in which the CdS is saturated with iodine at low pCd (=high pS2) but unsaturated at high pCd.The solubility of iodine in CdS is given by ct=1·73×1022pS2?1/8 exp (?1·045 eV/kT) cm?3 atm?1/8=4·62×1019pCd1/4 exp (?0·195 eV/kT) cm?3 atm1/4The formation of pairs (ISVCd)′ from IS· and VCd″ is governed by the equilibrium constant KP(I, V)=4 exp (≤1·1 eV/kT)If Cd diffusion occurs primarily by free vacancies, the Cd* tracer self diffusion leads to a vacancy mobility of (1·2±0·5)×10?5 cm2 sec?1 at 900°C, in agreement with results reported by Woodbury [12], but (7±3) times larger than reported by Kumar and Kroger [10]. 相似文献
7.
V. F. Synorov N. N. Bezryadin B. I. Sysoev N. A. Martynova 《Russian Physics Journal》1981,24(1):80-85
The current-voltage and high-frequency capacitance-voltage (C-V) characteristics have been used to investigate the electrical properties of thin Ga2Ses films in Me-Ga2Se3-Si structures (n and p type). The features of the high-frequency C-V dependences of the structures based on p-type Si are explained in the framework of a model of the MS' IS structure with donor type centers in the semiconducting S'film (the thickness of the S' film is comparable with the generalized screening length). It is shown that in the investigated structures the charge transport mechanism is due to ionization of volume centers (the activation energy of a deep donor center is 0.72 eV) in the Ga2Se3 film, the mechanism being enhanced by an electric field. Analysis of the high-frequency C-V characteristics showed that the majority carriers in the Ga2Se3 films are electrons with concentration 1012 cm–3; the concentration of the deep donor centers is 5·1016 cm–3.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 83–88, January, 1981. 相似文献
8.
用常压MOCVD在半绝缘GaAs衬底上生长了GaxIn1-xP(x=0.476~0.52)外延层,对外延层进行了X光双晶衍射、Hall和光致发光(PL)测试.77K下电子迁移率达3300cm2/V.s(浓度为1.4×1016cm-3).载流子浓度随生长温度升高,随Ⅴ/Ⅲ比的增大而降低,并提出P空位(Vp)是自由载流子的一个重要来源,17KPL谱中,Ga0.5In0.5P(Tg=650℃,Ⅴ/Ⅲ=70)的峰能为1.828eV,半峰宽为19meV.另外,在1.849eV处还有一较弱的峰,GaInP峰能和其计算的带隙最大相差113meV,这可能与GaInP中杂质或缺陷以及其中存在有序结构有关. 相似文献
9.
In this paper we review briefly the use of high resolution photoluminescence to study the behavior of shallow impurity states in compound semiconductors. As an illustration we focus our review on GaAs. The binding energies of the ground state and of several low-lying excited states of the impurity centers are determined by studying the radiative transitions associated with excitons bound to neutral donors or acceptors. The difference between the binding energies of different donors in GaAs is rather small. Thus to resolve transitions associated with different chemical donors a magnetic field is used. This has the effect of sharpening the transitions as well as increasing the separation between them. One can identify donors in samples with total impurity concentrations as high as 5X1015/cm3. The binding energies of different chemical acceptors in GaAs are much higher. Thus the radiative transitions associated with excitons bound to neutral acceptors can be resolved in zero magnetic field. Energy levels of shallow donors and acceptors in GaAs are reviewed. 相似文献
10.
利用变频导纳谱研究了γ辐照前后Hg1-xCdxTe(x=0.6)n+-on-p结中的深能级缺陷.辐照前其缺陷能级位置在价带上0.15 eV,俘获截面σp=2.9×10-18cm2,缺陷密度Nt=6.5×1015cm-3,初步认为是Hg空位或与其相关的复合缺陷;经过104Gy的γ辐照后其能级变得更深,在价带上0.19 eV,同时其俘获截面增加了近一个数量级,而缺陷密度基本上没有变化.γ辐照引入的这种能级变化最终使器件的性能(探测率)下降了1/2以上.
关键词: 相似文献
11.
S. A. Kazanskiĭ S. A. Klimin A. S. Shcheulin M. V. Narozhnyĭ A. I. Ryskin 《Optics and Spectroscopy》2008,104(6):861-865
The differences in the optical spectra of CdF2:In semiconductors with bistable DX centers (concentrated (CdF2)0.9(InF3)0.1 solid solutions) and “standard” samples with a lower impurity concentration used to record holograms are discussed. In contrast to the standard samples, in which complete decay of two-electron DX states and transfer of electrons to shallow donor levels may occur at low temperatures, long-term irradiation of a (CdF2)0.9(InF3)0.1 solid solution by UV or visible light leads to decay of no more than 20% deep centers. The experimental data and estimates of the statistical distribution of electrons over energy levels in this crystal give the total electron concentration, neutral donor concentration, and concentration of deep two-electron centers to be ~5 × 1018 cm?3, ~9 × 1017 cm?3, and more than 1 × 1020 cm?3, respectively. These estimates show that the majority of impurity ions are located in clusters and can form only deep two-electron states in CdF2 crystals with a high indium content. In this case, In3+ ions in a limited concentration (In3+ (~9 × 1017 cm?3) are statistically distributed in the “unperturbed” CdF2 lattice and, as in low-concentrated samples, form DX centers, which possess both shallow hydrogen-like and deep two-electron states. 相似文献
12.
The degree of compensation and ionization energy of two-electron DX centers in CdF2: In and CdF2: Ga semiconductors are determined by studying the statistical distribution of electrons localized on impurity levels. The sharp temperature dependence of the concentration of neutral donors observed in CdF2: Ga over the temperature range T = 250–400 K is explained by a high compensation degree, K ≥ 0.996. Thus, all Ga ions introduced into a CdF2 crystal lattice during crystal growth form shallow donor levels. However, the concentration of Ga ions that can form bistable DX centers is rather low and is close to the concentration of electrons injected into the crystal during additive coloring. In CdF2: In crystals, the degree of compensation is smaller than that in CdF2: Ga but is sufficiently high and the number of bistable DX centers is not limited. It is concluded that an extremely narrow impurity band forms in the CdF2: Ga semiconductor. For a total charged-impurity concentration of ~1020 cm?3, the width of the impurity band in CdF2: Ga is not likely to exceed ~0.02 eV. 相似文献
13.
The electrical resistivity and mobility of Cd and Zn doped CuInS2 single crystals grown by a Bridgman technique have been investigated. Crystals annealed in Cd or Zn vapor at high temperatures (~ 800°C) exhibit degenerate behaviour while those crystals annealed at more moderate temperatures (~650°C) show ionized impurity conduction with a shallow activation energy on the order of 0.004 eV. Resistivities as low as 0.15 Ω-cm and mobilities as high as 90 cm2/v-sec have been observed. 相似文献
14.
本文在20°—300°K研究了室温载流子浓度2×1012—1×1020cm-3含硼或磷(砷)Si的电学性质。对一些p-Si样品用弱场横向磁阻法及杂质激活能法进行了补偿度的测定,并进行了比较。从霍尔系数与温度关系的分析指出,对于较纯样品,硼受主能级的电离能为0.045eV,磷施主能级为0.045eV,在载流子浓度为1018—1019cm-3时发现了费米简并,对载流子浓度为2×1017—1×1018cm-3的p-Si及5×1017—4×1018cm-3的n-Si观察到了杂质电导行为。从霍尔系数与电导率计算了非本征的霍尔迁移率。在100°—300°K间,晶格散射迁移率μ满足关系式AT-a,其中A=2.1×109,α=2.7(对空穴);或A=1.2×108,α=2.0(对电子)。另外,根据我们的材料(载流子浓度在5×1011—5×1020cm-3间),分别建立了一条电阻率与载流子浓度及电阻率与迁移率的关系曲线,以提供制备材料时参考之用。 相似文献
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16.
P. M. Ratheesh Kumar C. Sudha Kartha K. P. Vijayakumar F. Singh D. K. Avasthi 《辐射效应与固体损伤》2013,168(7):635-644
ZnO thin films, irradiated by 80 MeV Ni+ ions, were analysed with the help of different characterization techniques like X-ray diffraction, optical absorption, transmission, photoluminescence (PL), electrical resistivity, photosensitivity (PS) and thermally stimulated current (TSC) measurements. Crystallinity and absorption edge were hardly affected by irradiation. PL spectrum of pristine sample showed a broad peak at 517 nm, whereas irradiated film had two emissions at 517 and 590 nm. Intensity ratio between these two emissions (I517/I590) decreased with the fluence, and finally at a fluence of 3×1013 ions/cm2, the emission at 517 nm completely disappeared. Electrical resistivity of the sample irradiated with a fluence of 1×1013 ions/cm2 drastically increased. However, on increasing the fluence to 3×1013 ions/cm2, resistivity decreased, probably due the onset of hopping conduction through defects. PS also decreased due to irradiation. TSC measurements on pristine sample could reveal only one defect level at 0.6 eV, due to interstitia1 zinc (ZnI). But, irradiation at a fluence of 1×1012 ions/cm2, resulted in three different defect levels as per TSC studies. Interestingly, the sample irradiated at a fluence of 3×1013 ions/cm2 had only one defect level corresponding to a deep donor. The possible origin of these defect levels is also discussed in the paper. 相似文献
17.
E. Pollert J. Hejtmaneck J.P. Doumerc J. Claverie P. Hagenmuller 《Journal of Physics and Chemistry of Solids》1983,44(4):273-279
Several techniques have been used in order to characterize the photoelectronic properties of a magnetoplumbite single crystal of composition Pb1.19Fe11.88O18.91. Measurements of electrical resistivity and thermoelectric power have shown between 77 and 300 K the compound to have n-type semiconducting properties. The I–V characteristics (in the dark and under illumination), the spectral response and the flat band potential have also been determined.The density of donors derived from Mott-Schottky plots (3.2 × 1019) is in good agreement with the value of the Fe2+ concentration (2.9 × 1019) obtained by chemical analysis. Electron affinity was found to be equal to 4.5 ± 0.2 eV. The photocurrent corresponding to the photoelectrolysis of water is due to indirect electronic transitions at 1.75, 2.1 and 2.4 eV. Evidence is given suggesting that these transitions correspond to lead-iron and/or iron-iron charge transfers. 相似文献
18.
H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):75-83
Absolute cross-sections for electron-impact ionization and dissociation of
C2H2+ and C2D2+ have been measured for electron energies
ranging from the corresponding thresholds up to 2.5 keV. The animated
crossed beams experiment has been used. Light as well as heavy fragment ions
that are produced from the ionization and the dissociation of the target
have been detected for the first time. The maximum of the cross-section for
single ionization is found to be (5.56 ± 0.03)× 10-17 cm2 around 140 eV. Cross-sections for dissociation of C2
H2+ (C2D2+) to ionic products are seen to decrease for two orders
of magnitude, from C2D+ (12.6 ± 0.3) × 10-17 cm2 over CH+(9.55 ± 0.06) × 10-17 cm2,
C+ (6.66 ± 0.05) × 10-17 cm2, C2+ (5.36 ± 0.27) × 10-17 cm2, H+ (4.73 ±
0.29) × 10-17 cm2 and CH2+ (4.56 ± 0.27) × 10-18 cm2 to H2+ (5.68 ± 0.49) ×
10-19 cm2. Absolute
cross-sections and threshold energies have been compared with the scarce
data available in the literature. 相似文献
19.
The optical properties of thick sputtered films (~30μ) of amorphous Ge, grown with different substrate temperatures (0ˇ-T sˇ-350°C), were obtained between 0·05 and 4·5 eV by a combination of reflectance, transmittance and ellipsometric measurements. The refractive index at 0·15 eV decreases monotonically with increasing T s, or equivalently, with increasing density, and is 4·13±0·05 eV in the highest density films. The absorption edge is approximately exponential (102?α?104 cm?1) but shifts monotonically to higher energy and increases in slope with increasing T s. Similarly, the peak in ε2 grows by about 10% and shifts by about 0·15 eV to higher energies, reaching a maximum of about 23 at 2·90±0·05 eV in the high density films. The peak in the transition strength ω2ε2 occurs at 4·2±0·2 eV in all films, but increases in magnitude with increasing T s. The sum rules for n eff(ω) and ε0,eff(ω) are evaluated for ▄ω?5 eV and vary monotonically with T s. These trends are neither compatible with Galeener's void resonance theory nor with changes in the oxygen content of the films, determined by the examination of absorption peaks at 0·053 eV and 0·09 eV. An explanation, suggested here and expanded in I, is based on the observed changes in the structure of the network and voids. 相似文献