ZnO:LiCl/p-Si薄膜中的施主-受主发光

用溶胶凝胶法(sol-gel technique)在p-Si上制备LiCl:ZnO薄膜.试样分别进行O2-600℃,O2-900℃热退火处理.在77～325K温度范围内作电流-温度(I-T)和深能级瞬态谱(DLTS)测量.DLTS测量获得的两种试样中存在一个稳定的深能级中心.(I-T)测量证实这个深能级中心是与ZnO的本征缺陷相关的.室温PL谱测量得到两种试样存在较强的深能级发光,而紫外发光较弱.由实验结果推测,试样主要的深能级发光过程是电子从双离化Zni**施主能级向单离化V'zn受主能级的跃迁.在O2气氛退火作用下深能级的发光强度增强.     

ZnO:LiCl/p-Si薄膜中的施主-受主发光

用溶胶凝胶法(sol-gel technique)在p-Si上制备LiClZnO薄膜.试样分别进行O2-600℃,O2-900℃热退火处理.在77～325K温度范围内作电流-温度(I-T)和深能级瞬态谱(DLTS)测量.DLTS测量获得的两种试样中存在一个稳定的深能级中心.(I-T)测量证实这个深能级中心是与ZnO的本征缺陷相关的.室温PL谱测量得到两种试样存在较强的深能级发光,而紫外发光较弱.由实验结果推测,试样主要的深能级发光过程是电子从双离化Zni**施主能级向单离化V'zn受主能级的跃迁.在O2气氛退火作用下深能级的发光强度增强.     

GaAs/Si/AlAs异质结的DLTS实验研究

利用深能级瞬态谱(DLTS)技术研究了Si夹层和GaAs层不同生长温度对GaAs/AlAs异质结晶体品质的影响.发现Si夹层的引入并没有引起明显深能级缺陷,而不同温度下生长的GaAs/Si/AlAs异质结随着温度的降低,深能级缺陷明显增加,并进行了分析,得到深能级是由Ga空位引起的,在600℃时生长的晶体质量最佳.     

MOCVD生长的硅衬底上GaAlAs/GaAs单量子阱和多量子阱激光器深能级研究

应用深能级瞬态谱(DLTS)技术研究经MOCVD生长的硅衬底上GaAlAs/GaAs 单量子阱和多量子阱激光器深能级.样品的 DLTS谱表明,在激光器的量子阱和 n-GaAlAs 限制层里均存在着一个浓度和俘获截面较大的高温电子陷阱,该陷阱可能与MOCVD生长工艺和质子轰击引进的损伤有关,它直接影响激光器的性能.DX中心和高温电子陷阱在量子阱里可能局域在GaAlAs/GaAs层的界面附近.     

CWCO_2激光在硅中引入的位错深能谱研究

用高功率密度的CWCO_2激光扫描在硅中引入了较单纯清洁的位错,并利用DLTS技术对其深能级谱进行了测量.在p型和n型硅中分别测到 E_v+0.33eV和 E_c-0.37eV,E_c-0.50eV三个深能级谱峰.实验结果表明,位错线上的断键是重构的,重构后只有少部分位错态是电活性的.氢等离子体退火对电活性的位错态有显著的钝化作用.     

用Laplace谱研究缺陷深能级精细结构

用Laplace谱隐谱仪（LDS）实验研究了GaAsP中Fe深受主上空穴发射和AlGaAs中SnDX中心上电子发射引起的非指数瞬态,发现它们起因子混晶无序效应。与DLTS的单一谱峰比较,LDS谱呈现出多峰结构,由深能级上空穴与电子热发射率随温度关系的直线拟合,得到多峰结构各峰谱的激活能,认为它们反映杂质深中心与其近邻原子的不同结构。研究表明,LDS适用于深能级精细结构的研究。     

发光二极管电子辐照后缺陷行为的DLTS研究

采用DLTS(深能级瞬态谱)与光功率测量方法,研究了发光二极管(GaP:N)经1MeV电子辐照后,其输出光功率的变化情况。实验发现,只在近乎不发光处于失效状态的二极管中进行DLTS测量时,才观察到深能级,数量不少于五个(E_1～E_5),这些深能级在热处理中的变化行为是:浓度随退火温度升高和退火时间延长而降低,500k退火后,除E_5能级外,其余深能级基本消失。另外还发现在正向注入电流的情况下,E_1和E_4能级均很快消失。     

(Ga,Al)As/GaAs及GaInAsP/InP激光器中的深能级

采用深能级瞬态谱技术(DLTS),测定了用水平液相外延法生长的四层结构Ga_(0.7)Al_(0.3)A_3/GaAs,Ga_(0.26)In_(0.74)As_(0.6) P_(0.4)/InP 宽接触及质子轰击条形双异质结激光器中的深能级,对于这些深能级所引起的激光器退化问题进行了初步研究和讨论.     

硅基氧化锌薄膜中的发光和复合中心

报道了用MOCVD方法制备的硅基ZnO薄膜中的中性施主-价带D0h发光.ZnO/p-Si结构经空气中700 ℃退火1h,然后进行X射线衍射(XRD)、光致发光(PL)谱和I-V特性测量.实验得到不同载气流量制备的样品都具有整流特性.深能级瞬态谱(DLTS)测量探测到各样品中存在两个施主深能级E1和E2.相应的室温PL谱测量显示样品近带边发射包含不同的发光线.利用高斯拟合方法,样品S2a的PL谱分解为三条发光线b,c和d,其中发光线b可归结为ZnO中的激子发射;DLTS测量得到的施主能级E1与发光线c和d的局域态电离能Ed相关,为D0h中心.此外,实验揭示E2能级的相对隙态密度与PL谱的发光强度成反比,表明深能级E2具有复合中心性质.     

InP中的深能级杂质与缺陷

综述了近年来关于InP中深能级缺陷和杂质的研究工作。讨论了深能级杂质及缺陷对InP材料性能的重要影响;介绍了深能级瞬态谱(DLTS)、光致发光谱(PL)、热激电流谱(TSC)、正电子寿命谱(PAS)、正电子深能级瞬态谱(PDLTS)等几种研究深中心的方法在研究InP时的某些特点;综合深能级缺陷和电学性质的测试结果,证明了半绝缘InP单晶材料的电学性能、热稳定性、均匀性等与材料中一些深能级缺陷的含量密切相关;分析了对掺铁和非掺退火两种半绝缘InP材料中深能级缺陷对电学补偿的影响;评述了对InP中的一些深中心所取得的研究成果和半绝缘InP的形成机理。     

脉冲激光烧蚀沉积ZnSe薄膜的研究

用 2 48nm的KrF准分子脉冲激光烧蚀ZnSe靶材沉积ZnSe薄膜。靶采用多晶ZnSe片 ,衬底采用抛光GaAs(10 0 )。衬底预处理采用化学刻蚀和高温处理。原子力显微镜 (AFM )观察显示在GaAs(10 0 )沉积的ZnSe薄膜的平均粗糙度为 3～ 4nm。X射线衍射 (XRD)结果表明ZnSe薄膜 (4 0 0 )峰的半高宽 (FWHM)为 0 4°～ 0 5°。对激光烧蚀团束的四极质谱分析表明烧蚀团束主要由Zn ,Se和 2Se组成 ,并由此推断ZnSe薄膜的二维生长模式。     

Studies of deep centers in dilute GaAsN and InGaAsN films grown by molecular beam epitaxy

Deep levels spectra DLTS, 77 K photoluminescence (PL) spectra and photosensitivity were measured for GaAsN and InGaAsN films with low N and In concentration grown by molecular beam epitaxy and in GaAs films grown on GaAsN buffer. It is shown that the bandedge luminescence intensity is greatly decreased in GaAsN, GaAs/GaAsN and particularly in InGaAsN structures compared to the homoepitaxial GaAs. Comparison of the DLTS and PL spectra strongly suggests that the main recombination center in such films is the EL3-like electron trap whose concentration greatly increases upon In and N incorporation into the solid solution. Based on published results the trap is associated with substitutional oxygen on As site and the results are discussed in view of such possible assignment.     

Optical Spectroscopy of Schottky Nanostructures Au/GaAs: Plasmon Resonances and Anisotropy

Semiconductors - The Schottky nanostructures Au/GaAs with Au nanoclusters are prepared by annealing of thin gold films deposited on nitridized GaAs(001) surface. The nanostructures are diagnosed...     

Group III alkyl source purity effect on the quality of GaAs grown with tertiarybutylarsine

We have grown unintentionally doped GaAs films using tertiarybutylarsine (tBAs) or arsine reacted with clean or silicon contaminated triethylgallium. Hall and SIMS data along with photoluminescence spectra show that the silicon contaminant level in GaAs MOCVD layers grown with tBAs is higher than for layers grown using arsine. Thus, high purity in the triethylgallium source is more critical for high purity GaAs films when using tBAs than when using arsine.     

An Apparatus for the Production and Ion Bombardment of Thin Films†

This communication describes a versatile apparatus for the production of thin polycrystalline metallic films under conditions of high purity. The apparatus includes facilities for film preparation by evaporation and cathodic sputtering and for ion bombardment of the films under the same conditions of purity as obtained during preparation. The films can also be annealed before and after ion bombardment, although at this stage of the programme these facilities have not been fully used. Electrical conductivity measurements of the films can be made in situ and some preliminary data on the effects of ion bombardment on the electrical conductivity of thin metallic films are reported.     

The <Emphasis Type="Italic">U</Emphasis> peak in the DLTS spectra of <Emphasis Type="Italic">n</Emphasis>-GaAs irradiated with fast neutrons and 65-MeV protons

The origin of a broad U band in spectra obtained using deep-level transient spectroscopy (DLTS) of n-GaAs irradiated with fast neutrons and 65-MeV protons was investigated. It is believed that this band is presumably a superposition of two peaks related to two defects P2 and P3 which have been well documented in GaAs and reside within defect clusters. The DLTS spectra were calculated taking into account the nonuniform distribution of these defects in a sample and the built-in electric fields induced by corresponding inhomogeneities.     

Coupling of electron states in the InAs/GaAs quantum dot molecule

Deep level transient spectroscopy (DLTS) is used to study electron emission from the states in the system of vertically correlated InAs quantum dots in the p-n InAs/GaAs heterostructures, in relation to the thickness of the GaAs spacer between the two layers of InAs quantum dots and to the reverse-bias voltage. It is established that, with the 100 Å GaAs spacer, the InAs/GaAs heterostructure manifests itself as a system of uncoupled quantum dots. The DLTS spectra of such structures exhibit two peaks that are defined by the ground state and the excited state of an individual quantum dot, with energy levels slightly shifted (by 1–2 eV), due to the Stark effect. For the InAs/GaAs heterostructure with two layers of InAs quantum dots separated by the 40 Å GaAs spacer, it is found that the quantum dots are in the molecule-type phase. Hybridization of the electron states of two closely located quantum dots results in the splitting of the levels into bonding and antibonding levels corresponding to the electron ground states and excited states of the 1s ⁺, 1s ^?, 2p ⁺, 2p ^?, and 3d ⁺ types. These states manifest themselves as five peaks in the DLTS spectra. For these quantum states, a large Stark shift of energy levels (10–40 meV) and crossing of the dependences of the energy on the electric field are observed. The structures with vertically correlated quantum dots are grown by molecular beam epitaxy, with self-assembling effects.     

Investigation of DX centers in modulation-doped field-effect transistor-type Al0.3Ga0.7As/GaAs heterostructures using a fourier-transform deep level transient spectroscopy system

Al_0.3Ga_0.7As:Si/GaAs modulation-doped field-effect transistor-type heterostructures were grown using two different growth temperatures (500 and 620°C) and three doping modes (δ-doping, pulse-doping, and uniform-doping). Deep level transient spectroscopy (DLTS) measurements were performed on these structures using a new Fourier-analysis method. Up to four DLTS peaks, related to the different possible configurations of the nearest Al and Ga neighbors around each DX site, were observed. Both the growth temperature and the doping-mode are found to affect the DLTS spectra, in particular the number of observed peaks and their width. These results are interpreted in terms of the different mobilities of the Si doping atoms on the surface during growth.     

GaAs solar cells grown on Si substrates for space use

GaAs single‐junction and InGaP/GaAs multi‐junction thin‐film solar cells fabricated on Si substrates have great potential for high‐efficiency, low‐cost, lightweight and large‐area space solar cells. Heteroepitaxy of GaAs thin films on Si substrates has been examined and high‐efficiency GaAs thin‐film solar cells with total‐area efficiencies of 18·3% at AM0 and 20·0% at AM 1·5 on Si substrates (GaAs‐on‐Si solar cells) have been fabricated. In addition, 1‐MeV electron irradiation damage to GaAs‐on‐Si cells has been studied. The GaAs‐on‐Si cells are found to show higher end‐of‐life efficiency than the conventional GaAs cells fabricated on GaAs substrates (GaAs‐ on‐GaAs cells) under high‐fluence 1‐MeV electron irradiation of more than 1 × 10¹⁵ cm⁻². The first space flight to make use of them has been carried out. Forty‐eight 2 × 2 cm GaAs‐on‐Si cells with an average AM0 total‐area efficiency of 16·9% have been evaluated in the Engineering Test Satellite No.6 (ETS‐VI). The GaAs‐on‐Si cells have been demonstrated to be more radiation‐resistant in space than GaAs‐on‐GaAs cells and 50, 100 and 200‐μm‐thick Si cells. These results show that the GaAs‐on‐Si single‐junction and InGaP/GaAs‐on‐Si multi‐junction cells have great potential for space applications. Copyright © 2001 John Wiley & Sons, Ltd.