高阻n型硅的电子辐照

研究了高阻区熔和直拉单晶(扩铝)的P~+n管经电子辐照后产生的缺陷能级和它们的退火特性.区熔单晶中辐照生成的主要缺陷能级为 E:-0.43eV (双空位)和 E_v+ 0.49eV.在300℃退火后,这些能级的浓度与未退火前基本相同.直拉单晶中辐照生成的缺陷能级为E_c-0.18eV (氧空位对)和 E_v+ 0.49eV.在200℃以上退火后,氧空位明显减小并在300℃消失.     

低剂量中子辐照氢气氛和氩气氛生长区熔硅的深能级瞬态谱研究

用深能级瞬态谱研究了如下三种N型区熔硅在低剂量中子辐照下的电子陷阱及其退火行为,(1)氩气氛生长,(2)氢气氛生长,(3)氢气氛生长并在中照前作650℃/30分热处理.含氢样品中A中心的生成率约为同剂量中照不含氢样品的50％.由于热释放空位,从室温到190℃热退火过程中A中心和双空位的浓度随退火温度的升高而增加.当退火温度高于230℃,中照含氢硅中A中心和双空位浓度的下降比不含氢硅样品要快得多,这可用原子氢的扩散加速了对缺陷的钝化来解释.等时退火到高于250℃,氢气氛和氩气氛生长区熔硅样品都出现了新的电子陷阱,对它们的可能结构进行了讨论.     

硅中激光辐照引进的点缺陷

利用深能级瞬态谱(DLTS)证实:经染料脉冲激光辐照,红宝石脉冲激光辐照,连续Nd:YAG激光辐照的P型硅样品,存在深中心缺陷,主要是:(E_v+0.14cV)、(Ev+ 0.19eV)和(Ev+ 0.24eV).从这些深中心缺陷的不同淬火和退火行为,可以认为缺陷中心主要是样品在激光退火过程中产生的过饱和空位所形成的,而且可能是与某种大空位团有关.     

中子辐照硅的正电子湮没寿命谱研究

研究了中子辐照硅中正电子湮没寿命谱的等时退火特性,得到与文献[1]不相同的结果.实验资料对比表明,本工作的结果与EPR、IR、DLTS的实验能更好地符合.对[1]中的双空位运动形成四空位的模型提出质疑.指出中子能谱不同很可能是导致缺陷俘获态寿命退火特性相异的重要原因.     

质子注入直拉硅中缺陷的研究

对比电子辐照和氦、硼离子注入,研究了质子注入n型和P型直拉硅中产生的缺陷及其退火行为.指出我们所观察到的n型样品中的电子陷阱E(0.30)是质子注入所特有的,它很可能是与氢有关的深能级.与电子辐照对比,离子注入在E(0.41)附近引入了除双空位及磷空位以外的新的缺陷.质子注入引入的氢能使n型样品中各电于陷阱的退火温度有不同程度的降低;在P型样品中,当质子注入剂量为5 × 10~(10)/cm~2与1.5 × 10~(11)/cm~2时,各空穴陷阱的退火温度降低并会聚在150℃,但当质子注入剂量大于或等于5 × 10~(11)/cm~2时,注入的氢对各空穴陷阱的退火没有明显的影响.对以上现象作了分析与讨论.     

As~+沟道注入硅(100)的损伤、二次缺陷及载流子分布特征

用电容及电流DLTS方法测量了B~+、P~+离子注入掺硼p-Si中引进的空穴缺陷能级及其退火行为.在两种离子注入样品中都测到的空穴陷阱有七个,除了常见的辐照缺陷V.O.C受主H_4(0.35)、V.O.B复合团H_5(0.29)及V_2~+双空位单受主H_(72)(0.21)外,还测到其它四个能级H_0(0.56)、H_3(0.47)、H_6(0.25)、H_(73)(0.15).此外,在注B~+样品中还测到H_1(0.57)、H_2(0.53),在注P~+样品中有三个能级H_2~＇(0.61)H_(71)~＇(0.20)、H_8~＇(0.11),其中H_8~＇浓度很小.在600℃退火后,缺陷浓度均在10~(13)cm-~(-3)以下或者完全消失.与已有的工作比较,本文所测得的各种缺陷有较高的退火温度.     

中子辐照砷化镓的快速退火行为的正电子寿命研究

用正电子湮没技术研究了中子辐照半绝缘ＧａＡｓ的快速退火行为。结果表明：辐照引入的空位缺陷浓度与辐照剂量有关。退火过程中的空位团的分解和聚合与退火温度和辐照剂量关。     

中子辐照氢气区熔硅单晶退火行为的正电子湮没研究

用正电子湮没寿命和多普勒加宽方法研究了中子辐照氢气区熔硅单晶的等时退火行为.观测到324±12ps的寿命组分是正电子在双空位湮没寿命,是主要的长寿命组分.450±14ps是正电子在四空位湮没寿命。324ps寿命组分在450℃附近退火消失后,它又以较高的强度在530—800℃的温度范围出现.对不同温度退火的晶体取得的基块寿命不是常数值而是随退火温度有规律的变化.这些异常的退火行为归结为中子辐照硅中所诱导的空位缺陷与氢的相互作用及其对晶格的影响.     

电子和中子辐照n型6H-SiC的光致发光谱

对用电子能量为1.7,0.5和0.4MeV的电子辐照和中子辐照后的n型6H-SiC样品进行低温光致发光研究.对于Ee≥0.5MeV电子辐照和中子辐照后的样品,首次发现了位于478.6/483.3/486.1n m的S1/S2/S3谱线.对样品进行热退火研究表明S1/S2/S3谱线在500℃下消失,而退火温度高于700℃时D1中心出现.考虑到产生C空位和Si空位所需的位移阈能以及热退火行为,说明S1/S2/S3为初级Si空位初级缺陷,而D1中心为二次缺陷.     

电子和中子辐照n型6H-SiC的光致发光谱

对用电子能量为1.7,0.5和0.4MeV的电子辐照和中子辐照后的n型6H-SiC样品进行低温光致发光研究.对于Ee≥0.5MeV电子辐照和中子辐照后的样品,首次发现了位于478.6/483.3/486.1n m的S1/S2/S3谱线.对样品进行热退火研究表明S1/S2/S3谱线在500℃下消失,而退火温度高于700℃时D1中心出现.考虑到产生C空位和Si空位所需的位移阈能以及热退火行为,说明S1/S2/S3为初级Si空位初级缺陷,而D1中心为二次缺陷.     

The influence of plasma etching on trap levels in InP

Electroreflectance (ER) and deep level transient spectroscopy (DLTS) were carried out to characterize the effects of CF₄ plasma etching on defect levels in InP. Different chamber gas pressures were conducted to study effects on the etching result. Similar ER spectra were obtained from the starting InP wafer and the wafer after plasma etching plus rapid thermal annealing (RTA) which showed good restoration of material properties by RTA. Two impurity of structural related features, T1 and T2, were observed from these ER spectra at energy positions about 0.112 and 0.178 eV below bandgap. Two trap levels, El and E2, with activation energy 0.15 and 0.55 eV, were detected from the initial wafer by DLTS. Trap El may correlate with the Tl and T2 levels observed by ER. Similar traps were found in plasma etched samples after rapid thermal annealing with one of the DLTS peaks labeled E2 shifted to the higher temperature side as the plasma etching chamber pressure increased. We identified El to be a residual electron trap from material growth and E2 to be an interface trap arising from Schottky diode fabrication.     

Uniformity of deep levels in semi-insulating InP obtained by multiple-step wafer annealing

The uniformity of deep levels in semi-insulating InP wafers, which have been obtained by multiple-step wafer annealing under phosphorus vapor pressure, was studied using the thermally stimulated current (TSC) and photoluminescence (PL) methods. Only three traps related to Fe, T₀ (ionization energy E_i=0.19 eV), T₁ (0.25 eV), and T₂ (0.33 eV), probably forming complex defects, were observed in the wafer and they exhibited a relatively uniform distribution. PL spectra relating to phosphorus vacancies observed in some regions of the wafer are correlated with a small TSC signal having an ionization energy of 0.43 eV.     

Phase transformation from cubic ZnS to hexagonal ZnO by thermal annealing

We have investigated the mechanism of phase transformation from ZnS to hexagonal ZnO by hightemperature thermal annealing. The ZnS thin films were grown on Si(001) substrate by thermal evaporation system using ZnS powder as source material. The grown films were annealed at different temperatures and characterized by X-ray diffraction(XRD), photoluminescence(PL), four-point probe, scanning electron microscope(SEM) and energy dispersive X-ray diffraction(EDX). The results demonstrated that as-deposited ZnS film has mixed phases but high-temperature annealing leads to transition from ZnS to ZnO. The observed result can be explained as a twostep process:(1) high-energy O atoms replaced S atoms in lattice during annealing process, and(2) S atoms diffused into substrate and/or diffused out of the sample. The dissociation energy of ZnS calculated from the Arrhenius plot of 1000/T versus log(resistivity) was found to be 3.1 eV. PL spectra of as-grown sample exhibits a characteristic green emission at 2.4 eV of ZnS but annealed samples consist of band-to-band and defect emission of ZnO at 3.29 eV and 2.5 eV respectively. SEM and EDX measurements were additionally performed to strengthen the argument.     

Tuning the Properties of CZTS Films by Controlling the Process Parameters in Cost-Effective Non-vacuum Technique

Highly dispersive Cu₂ZnSnS₄ (CZTS) nanoparticles were successfully synthesized by a simple solvothermal route. A low cost, non-vacuum method was used to deposit CZTS nanoparticle ink on glass substrates by a doctor blade process followed by selenization in a tube furnace to form Cu₂ZnSn (S,Se)₄ (CZTSSe) layers. Different selenization conditions and particle concentrations were considered in order to improve the crystallinity and surface morphology; the annealing temperature was varied between 400°C and 550°C and the annealing time was varied between 5 min and 20 min in a selenium-nitrogen atmosphere. The influence of annealing conditions on structural, compositional, optical and electrical properties of CZTSSe thin films was studied. An improvement in the structural and surface morphology was observed with increasing of annealing temperature (up to 500°C). An enhancement in the crystallinity and surface morphology were observed for thin films annealed for 10–15 min. Absorption study revealed that the band gap energy of as-deposited CZTS thin film was approximately 1.43 eV, while for CZTSSe thin films it ranged from 1.15 eV to 1.34 eV at different annealing temperatures, and from 1.33 eV to 1.38 eV for different annealing times.     

Effects of Illumination on Ar<Superscript>+</Superscript>-Implanted <Emphasis Type="Italic">n</Emphasis>-Type 6H-SiC Epitaxial Layers

Argon ions were implanted into n-type 6H-SiC epitaxial layers at 600°C. Postimplantation annealing was carried out at 1,600°C for 5 min in an Ar ambient. Four implantation-induced defect levels were observed at E_C-0.28 eV, E_C-0.34 eV, E_C-0.46 eV, and E_C-0.62 eV by deep level transient spectroscopy. The defect center at E_C-0.28 eV is correlated with ED₁/ED₂ and with ID₅. The defect at E_C-0.46 eV with a capture cross section of 7.8 × 10⁻¹⁶ cm² is correlated with E1/E2, while the defect at E_C-0.62 eV with a capture cross section of 2.6 × 10⁻¹⁴ cm² is correlated with Z1/Z2. Photo deep level transient spectroscopy was also used to study these defects. Upon illumination, the amplitudes of the deep level transient spectroscopy (DLTS) peaks increased considerably. Two emission components of Z1/Z2 were revealed: one fast and the other slow. The fast component could only be observed with a narrow rate window. In addition, a new defect was observed on the low-temperature side of the defect at E_C-0.28 eV when the sample was illuminated. [rl](Received ...; accepted ...)     

Neutron-induced trapping levels in aluminum gallium arsenide

Deep level transient spectroscopy (DLTS) measurements have been performed on a variety of Al_xGa_1-xAs p-n junctions prior to and following a series of fast neutron irradiations at room temperature and subsequent isochronal anneals. In contrast with electron and proton irradiated GaAs, neutron irradiation produces a single, broad featureless DLTS band which is a majority carrier trap in both n and p type material. The characteristics of this neutron-induced trap are relatively independent of growth method, dopant type and concentration. In GaAs, the thermal emission energies of the trap are 0.58 to 0.68 eV depending on the particular junction. These energies increase with Al content to 0.94 eV at 20% Al. The trap introduction rate, which also increases with Al content, is 0.7 cm_-1 in GaAs. Isochronal annealing to temperatures as high as 400‡C results in a smaller FWHM of the DLTS band, a shift in the peak to higher temperatures, and a modest decrease in magnitude. Above 400‡C the magnitude decreases rapidly, suggesting a similarity with the antisite defect, As_Ga, which has been observed to anneal in this range.     

Characterization of electron traps in plasma-treated AlInAs

Electron traps have been investigated for molecular beam epitaxially grown n-AlInAs by isothermal capacitance transient spectroscopy measurement. Two traps, EOl(Ec−0.44 eV) and EO2(Ec−0.52 eV), appear for oxygen-plasma treated samples in addition to El(Ec−0.47 eV) and E2(Ec−0.69 eV) traps detected for control (as-chemically etched) sample. On the other hand, the EO1 trap is not detected for Ar plasma-treated sample. This suggests that the EO1 is generated by reaction of atomic oxygen with AllnAs and that the EO2 trap is induced by plasma damage. It is found that a reduction in the densities of the four traps occurs due to annealing subsequently after oxygen plasma treatment.     

Study of deep level defect behavior in undoped n-InP (1 0 0) after rapid thermal annealing

The effects of rapid thermal annealing on deep level defects in the undoped n-type InP with Ru as Schottky contact metal have been characterized using deep level transient spectroscopy (DLTS). It is observed that the as-deposited sample exhibit two deep levels with activation energies of 0.66 and 0.89 eV. For the samples annealed at 300 °C and 400 °C, a deep level is identified with activation energies 0.89 and 0.70 eV, respectively below the conduction band. When the sample is annealed at 500 °C, three deep levels are observed with activation energies 0.25, 0.32 and 0.66 eV. Annealing of the sample at 300 °C, orders the lattice of as-grown material by suppressing the defect 0.66 eV (A1) which is found in the as-deposited sample. The trap concentration of the 0.89 eV deep levels is found to be increased with annealing temperature. The deep level 0.32 eV may be due to the lattice defect by thermal damage during rapid thermal annealing process such as vacancies, interstitials and its complexes, indicating the damage of the sample after annealing at 500 °C. The defects observed in all the samples are possibly due to the creation of phosphorous vacancy or phosphorous antisite.     

An investigation of molecular beam epitaxy “in-situ” grown Ag/GaAs schottky diodes

Electrical properties of molecular beam epitaxy “in-situ” grown Ag on (001) GaAs Schottky diodes were investigated. X-ray rocking curves show a (111) main peak for “in-situ” Ag grown at low temperature. During annealing, the main peak of Ag rotates from (111) to (200) to closely match that of the underlying GaAs lattice. The barrier height, 0.991 eV (determined by C-V measurement), decreases whereas doping concentration increases with increasing annealing temperature. Interdiffusion and the formation of some compound phases were also observed during annealing. A simple model, in which Ga dissociates from GaAs resulting in an increase in uncompensated ions at the metal-semiconductor interface, is proposed to explain the observation that carrier concentrations increase after annealing.     

Deep Radiation-Induced Defect Centers Created by a Fast Neutron Flux in CdZnTe Single Crystals

The effect of a fast neutron flux (Φ = 10¹⁴–10¹⁵ cm^–2) on the electrical and photoluminescence properties of p-CdZnTe single crystals is studied. Isothermal annealing is performed (T = 400–500 K), and the activation energy of the dissociation of radiation-induced defects is determined at E_D ≈ 0.75 eV.