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1.
We have investigated the structural and electrical characteristics of the Ag/n-TiO2/p-Si/Al heterostructure. Thin films of pure TiO2 were deposited on p-type silicon (100) by optimized pulsed laser ablation with a KrF-excimer laser in an oxygen-controlled environment. X-ray diffraction analysis showed the formation of crystalline TiO2 film having a tetragonal texture with a strong (210) plane as the preferred direction. High purity aluminium and silver metals were deposited to obtain ohmic contacts on p-Si and n-TiO2, respectively. The current–voltage (I–V) characteristics of the fabricated heterostructure were studied by using thermionic emission diffusion mechanism over the temperature range of 80–300 K. Parameters such as barrier height and ideality factor were derived from the measured I–V data of the heterostructure. The detailed analysis of I–V measurements revealed good rectifying behavior in the inhomogeneous Ag/n-TiO2/p-Si(100)/Al heterostructure. The variations of barrier height and ideality factor with temperature and the non-linearity of the activation energy plot confirmed that barrier heights at the interface follow Gaussian distributions. The value of Richardson’s constant was found to be 6.73 × 105 Am?2 K?2, which is of the order of the theoretical value 3.2 × 105 Am?2 K?2. The capacitance–voltage (C–V) measurements of the heterostructure were investigated as a function of temperature. The frequency dependence (Mott–Schottky plot) of the C–V characteristics was also studied. These measurements indicate the occurrence of a built-in barrier and impurity concentration in TiO2 film. The optical studies were also performed using a UV–Vis spectrophotometer. The optical band gap energy of TiO2 films was found to be 3.60 eV. 相似文献
2.
T. A. Pagava 《Semiconductors》2007,41(6):631-633
p-Si single crystals grown by the Czochralski method were studied; the hole concentration in these crystals was p = 6 × 1013 cm?3. The samples were irradiated with 8-MeV electrons at 300 K and were then annealed isochronously in the temperature range T ann = 100–500°C. The studies were carried out using the Hall method in the temperature range of 77–300 K. It is shown that annealing of divacancies occurs via their transformation into the B s V 2 complexes. This complex introduces the energy level located at E v + 0.22 eV into the band gap and is annealed out in the temperature range of 360–440°C. It is assumed that defects with the level E v + 0.2 eV that anneal out in the temperature range T ann = 340–450°C are multicomponent complexes and contain the atoms of the doping and background impurities. 相似文献
3.
The capabilities of admittance spectroscopy for the investigation of a-Si:H/c-Si heterojunctions are presented. The simulation and experimental results, which compare very well, show that the admittance technique is sensitive to the parameters of both the a-Si:H layer and the a-Si:H/c-Si interface quality. In particular, the curves showing capacitance versus temperature have two steps, accompanied by two bumps in the temperature dependence of the conductance. The first step, occurring in the low temperature range (100–200 K), is related to the transport and response of gap states in the a-Si:H layer. The second step, occurring at higher temperatures (>200 K), is caused by a carrier exchange with interface states and appears when the interface defect density exceeds 5 × 1012 cm?2. Then, the interface defects affect band bending, and, thus, the activation energy of de-trapping, which favors exchange with electrons from a-Si:H and holes from c-Si, respectively, for an increasing defect density. 相似文献
4.
Capture centers (traps) are studied in silicon-on-insulator (SOI) structures obtained by bonding and hydrogen-induced stratification. These centers are located at the Si/SiO2 interface and in the bulk of the split-off Si layer. The parameters of the centers were determined using charge deep-level transient spectroscopy (Q-DLTS) with scanning over the rate window at fixed temperatures. Such a method allows one to study the traps near the Si midgap at temperatures near 295 K. It is shown that the density of traps with a continuous energy spectrum, which are located at the bonded Si/SiO2 interface, decreases by more than four orders of magnitude at the mid-gap compared with the peak density observed at the activation energy E a ≈0.2–0.3 eV. The capture centers are also found in the split-off Si layer of the fabricated SOI structures. Their activation energy at room temperature is E a =0.53 eV, the capture cross section is 10?19 cm2, and the concentration is (0.7–1.7)×1013 cm?3. It is assumed that these capture centers are related to deep bulk levels induced by electrically active impurities (defects) in the split-off Si layer close to the Si/SiO2 interface. 相似文献
5.
The results of studying the electrical properties and isochronous annealing of p-ZnSnAs2 irradiated with H+ ions (energy E = 5 MeV, dose D = 2 × 1016 cm?2) are reported. The limiting electrical characteristics of irradiated material (the Hall coefficient R H (D)lim ≈ ?4 × 103 cm3 C?1, conductivity σ (D)lim ≈ 2.9 × 10?2 Ω?1 cm?1, and the Fermi level position F lim ≈ 0.58 eV above the valence-band top at 300 K) are determined. The energy position of the “neutral” point for the ZnSnAs2 compound is calculated. 相似文献
6.
The influence of hydrostatic pressure on the current–voltage characteristics of surface-barrier diode structures of the Sb–p-Si〈Mn〉–Au type are investigated. The potential-barrier height and the baric coefficient of its variation are found to be e?δ = 0.75 eV and δ =–1.54 × 10–11 eV/Pa, respectively. 相似文献
7.
The effect of oxygen on diffusion of sodium implanted into silicon is studied for the first time in the temperature range from 500 to 850°C. A high-resistivity p-Si (ρ > 1 kΩ cm) grown by the Czochralski method in a magnetic field (mCz) with the oxygen concentration ~3 × 1017 cm?3 was used. For comparison, we used silicon grown by the crucibleless floating zone method (fz). Temperature dependences of the effective diffusion coefficient of sodium in the mCz-Si and fz-Si crystals were determined and written as D mCz[cm2/s] = 1.12exp(?1.64 eV/kT) cm2/s and D fz[cm2/s] = 0.024exp(?1.29 eV/kT) cm2/s, respectively. It is assumed that larger values of diffusion parameters in oxygen-containing silicon are caused by formation of complex aggregates that contain sodium and oxygen atoms. 相似文献
8.
P. N. Brunkov A. A. Gutkin V. V. Chaldyshev N. N. Bert S. G. Konnikov V. V. Preobrazhenskii M. A. Putyato B. R. Semyagin 《Semiconductors》2005,39(9):1013-1016
Electron traps in low-temperature-grown ~40-nm-thick GaAs layers containing nanometer As-Sb clusters have been studied using deep-level transient spectroscopy. Measurements at various bias voltages and small-amplitude filling pulses have allowed the identification of two groups (T1 and T2) of traps with substantially different thermal electron emission rates. It is shown that the density of traps T2 (with an activation energy of 0.56 ± 0.04 eV and electron capture cross section of 2 × 10?13?10?12cm2) is ~2 × 1012cm?2, while the density of traps T1 (0.44 ± 0.02 eV and 2 × 10?14?10?13 cm2, respectively) is ten times lower. It is assumed that, according to the existence of the two cluster groups observed in the layers under study, traps T2 are associated with clusters 4–7 nm in diameter and traps T1, with clusters up to ~20 nm in diameter. 相似文献
9.
The current-voltage (I-V) characteristics of PbGa2Se4 single crystals grown by the Bridgman-Stockbarger method with a resistivity of 1010–1012 Ω cm were measured. The value of the majority carrier mobility μ=14 cm2 V?1 s?1, calculated by the differential method of analysis of I-V characteristics, makes it possible to evaluate a number of parameters: the carrier concentration at the cathode (nc0=2.48 cm?3), the width of the contact barrier dc=5.4×10?8 cm, the cathode transparency D c * =10?5–10?4 eV, and the quasi-Fermi level EF=0.38 eV. It is found that a high electric field provides the charge transport through PbGa2Se4 crystals in accordance with the Pool-Frenkel effect. The value of the dielectric constant calculated from the Frenkel factor is found to be equal to 8.4. 相似文献
10.
B. A. Komarov 《Semiconductors》2004,38(9):1041-1046
Deep-level transient spectroscopy is used to study the formation of complexes that consist of a radiation defect and a residual impurity atom in silicon. It is established that heat treatment of the diffused Si p+-n junctions irradiated with fast electrons lead to the activation of a residual Fe impurity and the formation of the FeVO (E0.36 trap) and FeV2 (H0.18 trap) complexes. The formation of these traps is accompanied by the early (100–175°C) stage of annealing of the main vacancy-related radiation defects: the A centers (VO) and divacancies (V2). The observed complexes are electrically active and introduce new electron (E0.36: E t e =E c -0.365 eV, σ n =6.8×10?15 cm2) and hole (H0.18: E t h =E v +0.184 eV, σ p =3.0×10?15 cm2) levels into the silicon band gap and have a high thermal stability. It is believed that the complex FeVO corresponds to the previously observed and unidentified defects that have an ionization energy of E t e =E c ?(0.34–0.37) eV and appear as a result of heat treatment of irradiated diffused Si p+-n junctions. 相似文献
11.
O. A. Parfenyuk M. I. Ilashchuk K. S. Ulyanitskiĭ P. M. Fochuk O. M. Strilchuk S. G. Krylyuk D. V. Korbutyak 《Semiconductors》2006,40(2):143-147
The CdTe:Si single crystals with Si concentration in the range of C Si 0 =2×1018–5×1019 cm?3 are grown by the Bridgman-Stockbarger method. The samples were of the n-and p-type with electrical conductivity σ=2×10?1–8×10?9 Ω?1 cm?1. Being heated in the temperature range 300–440 K, the p-CdTe crystals were annealed, and their conductivity decreased. The shape of the low-temperature (5–20 K) photoluminescence spectra of the samples are indicative of their high structural quality. The specific feature of the emission of the CdTe:Si crystals is its decrease in the intensity of all lines induced by donors as the samples are cut progressively closer to the ingot top. The results obtained indicate that the Si impurity, in contrast with Ge, Sn, and Pb, does not exhibit the compensating and stabilizing effect in CdTe. 相似文献
12.
The impact ionization of acceptors in aluminum-doped 4H-SiC epitaxial films (Al concentration 2 × 1015 cm?3) at a temperature of 77 K is studied. It is found that the impact-ionization coefficient exponentially depends on the reverse electric field: α p = α*pexp(?F*/F). The largest ionization coefficient is α* p = 7.1 × 106 cm?3 s?1, and the threshold field is F* = 2.9 × 104 V/cm. 相似文献
13.
A. V. Savitskii O. A. Parfenyuk M. I. Ilashchuk K. S. Ulyanitskii S. N. Chupyra N. D. Vakhnyak 《Semiconductors》2005,39(7):754-758
The electrical properties in the temperature range 295–430 K and low-temperature (4.2 K) photoluminescence of Cd1?xZnxTe:Cl semi-insulating crystals grown from melts with a variable impurity content (C Cl 0 = 5 × 1017–1 × 1019 cm?3) are investigated. Nonequilibrium processes leading to a decrease in carrier concentration are observed in all the samples at low temperatures (T = 330–385 K). These changes are reversible. The activation energy of these processes E a is found to be 0.88 eV. As with semi-insulating CdTe:Cl, the observed phenomena can be explained by a change in the charge state of background copper atoms: CuCd ? Cui. The introduction of Zn changes the ratio of the concentrations of shallow-level donors Cui and ClTe from their levels in the initial material. 相似文献
14.
N. A. Sobolev B. Ya. Ber A. M. Emel’yanov A. P. Kovarskiĭ E. I. Shek 《Semiconductors》2007,41(3):285-287
Multiple implantation of oxygen ions with energies of 0.1–1.5 MeV at doses of 7 × 1013?2 × 1014 cm?2 and subsequent annealing in a chlorine-containing atmosphere at 900°C for 4 h give rise to dislocation-related luminescence in p-Si. A p → n conductivity-type conversion is also observed in this case in the surface layer of Si, which indicates that electrically active donor centers are formed in the process. Preliminary heat treatment of wafers covered with an erbium-doped film of tetraethoxysilane (TEOS) in argon at 1250°C for 1 h does not preclude the appearance of dislocation-related luminescence, but affects the parameters of the dislocation-related lines (peak positions and intensities). 相似文献
15.
A. A. Gutkin M. É. Rudinsky P. N. Brunkov A. A. Klochikhin V. Yu. Davydov H. -Y. Chen S. Gwo 《Semiconductors》2008,42(12):1416-1419
Dependences of differential capacitance of the electrolyte-n-InN (0001) contact on the bias voltage are studied. Their analysis of the basis of a model similar to a model of the MIS structure shows that the energy spectrum of surface states of InN above the conduction band bottom can be represented by two, relatively narrow, bands of deep levels described by the Gaussian distribution. Parameters of these bands are as follows: the average energy counted from the conduction band bottom, ΔE 1 ≈ 0.15 eV and ΔE 2 ≈ 0.9 eV; and the mean-square deviation, ΔE 1 ≈ 0.15–0.25 eV and ΔE 2 ≈ 0.05–0.1 eV. The total density of states in the bands are (1–2.5) × 1012 and (0.2–4) × 1012 cm–2. 相似文献
16.
The distribution of charged centers N(w), quantum efficiency, and electroluminescence spectra of blue and green light-emitting diodes (LED) based on InGaN/AlGaN/GaN p-n heterostructures were investigated. Multiple InGaN/GaN quantum wells (QW) were modulation-doped with Si donors in GaN barriers. Acceptor and donor concentrations near the p-n junction were determined by the heterodyne method of dynamic capacitance to be about N A ≥ 1 × 1019 cm?3 ? N D ≥ 1 × 1018 cm?3. The N(w) functions exhibited maxima and minima with a period of 11–18 (±2–3 nm) nm. The energy diagram of the structures has been constructed. The shifts of spectral peaks with variation of current (J=10?6–3×10?2 A) are smaller (13–12 meV for blue and 20–50 meV for green LEDs) than the corresponding values for the diodes with undoped barriers (up to 150 meV). This effect is due to the screening of piezoelectric fields in QWs by electrons. The dependence of quantum efficiency on current correlates with the charge distribution and specific features in the current-voltage characteristics. 相似文献
17.
E. V. Bogdanova A. A. Volkova A. E. Cherenkov A. A. Lebedev R. D. Kakanakov L. P. Kolaklieva G. A. Sarov T. M. Cholakova A. V. Kirillov L. P. Romanov 《Semiconductors》2005,39(6):730-733
The possibility of fabricating heavily doped (N a ?N d ≥ 1 × 1019 cm?3) p+-4H-SiC layers on CVD-grown lightly doped n-4H-SiC layers by sublimation epitaxy has been demonstrated. It is shown that a Au/Pd/Ti/Pd contact, which combines a low specific contact resistance (~2 × 10?5 Ω cm2) with high thermal stability (up to 700°C), is the optimal contact to p-4H-SiC. The p-n structures obtained are used to fabricate packaged diodes with a breakdown voltage of up to 1400 V. 相似文献
18.
O. V. Aleksandrov 《Semiconductors》2002,36(1):21-25
Passivation of p-Si by hydrogen through its diffusion was simulated by solving diffusion-kinetic equations with allowance made for hydrogen-acceptor-pair formation, internal electric field, and the screening effect. Screening of hydrogen and acceptor ions by free carriers leads to a decrease in the radius of interaction between the ions and to the weakening of the concentration dependence of hydrogen diffusivity in heavily doped Si. At a binding energy of the pairs of 0.70–0.79 eV, calculated and experimental concentration profiles of holes and the hydrogen-acceptor pairs are in agreement over a wide range of boron concentrations, from 4×1014 to 1.2×1020 cm?3. The radius of the Coulomb interaction of hydrogen and boron ions is 35 Å in lightly doped Si and decreases as the dopant concentration increases. 相似文献
19.
Diffusion of Cr into epitaxial GaAs in an open system in the temperature range of 750–850°C was studied. Temperature dependences of the diffusion coefficient and solubility of Cr in GaAs were determined. Temperature dependences of the diffusion coefficient and solubility of Cr are described by the Arrhenius equation with the parameters D 0 = 1.9 × 109 cm2/s and E = 4.1 ± 0.2 eV for the diffusion coefficient and N 0 = 2.3 × 1024 cm?3 and E 0 = 1.9 ± 0.4 eV for solubility. The effect of protective SiO2 filmon the Cr diffusion coefficient and morphology of the GaAs surface after diffusion was studied. 相似文献
20.
Kh. T. Igamberdiev A. T. Mamadalimov R. A. Muminov T. A. Usmanov Sh. A. Shoyusupov 《Semiconductors》2003,37(1):28-30
The levels of vanadium in the band gap of n-and p-Si were determined using photocapacitance measurements. It is shown that vanadium introduces levels only in the upper half of the band gap of n-Si; these levels have ionization energies of about E c ?0.21 eV, E c ?0.32 eV, and E c ?0.52 eV. By contrast, V levels are located both in the upper and lower halves of the p-Si band gap: E c ?0.26 eV, E v +0.52 eV, E v +0.42 eV, and E v +0.31 eV. It is ascertained that the photoionization cross sections of all vanadium levels are larger for electrons than for holes. It is shown that the concentration of electrically active vanadium centers in n-and p-Si depends on both the concentration of shallow-level impurities and the time of vanadium diffusion into Si. 相似文献