高纯度砷化镓外延薄膜剩余受主杂质的研究

本文用光致发光法(4.2°K和1.8°K)研究高纯度LPE-GaAs和VPE-GaAs的剩余受主杂质。实验结果表明,高纯LPE-CaAs的剩余受主杂质为C、Si、Ge,而在AsCl3-Ga-H2系统中生长的高纯VPE-GaAs的剩余受主杂质为C、Zn、Si、Ge。但是在AsCl3-Ga-N2系统中生长的高纯VPE-GaAs只检测到受主杂质碳。本文还研究某些生长条件对杂质引入的影响。     

金属与半导体Ge欧姆接触制备、性质及其机理分析

金属与Ge材料接触时界面处存在着强烈的费米钉扎效应, 尤其与n型Ge形成的欧姆接触的比接触电阻率高, 是制约Si基Ge器件性能的关键因素之一. 本文对比了分别采用金属Al和Ni 与Si衬底上外延生长的p型Ge和n型Ge材料的接触特性. 发现在相同的较高掺杂条件下, NiGe与n型Ge可形成良好的欧姆接触, 其比接触电阻率 较 Al接触降低了一个数量级, 掺P浓度为2×10¹⁹ cm^-3时达到1.43×10^-5 Ω·cm². NiGe与p型Ge接触和Al接触的比接触电阻率相当, 掺B浓度为4.2×10¹⁸ cm^-3时达到1.68×10^-5 Ω·cm². NiGe与n型Ge接触和Al电极相比较, 在形成NiGe过程中, P杂质在界面处的偏析是其接触电阻率降低的主要原因. 采用NiGe作为Ge的接触电极在目前是合适的选择. 关键词： 金属与Ge接触性质 NiGe 比接触电阻率     

厚度对MOCVD生长InN薄膜位错特性与光电性质的影响

研究了金属有机物化学气相沉积法制备的不同厚度InN薄膜的位错特性与光电性质.基于马赛克微晶模型,通过X射线衍射非对称面摇摆曲线测量,拟合出样品刃型位错密度分别为4.2×10¹⁰cm^-2和6.3×10¹⁰cm^-2,并发现样品的微晶扭转角与位错密度随薄膜厚度增加而减小.通过室温霍尔效应测量得到样品载流子浓度分别为9×10¹⁸cm^-3和1.2×10¹⁸cm关键词： 氮化铟 位错 载流子起源 局域态     

退火对AlGaInP/GaInP多量子阱 LED外延片性能的影响

采用LP-MOCVD技术在n-GaAs衬底上生长了AlGaInP/GaInP多量子阱红光LED外延片.研究表明退火对外延片性能有重要影响.与未退火样品相比,460℃退火15min,外延片p型GaP层的空穴浓度由5.6×10¹⁸cm^-3增大到6.5×10¹⁸cm^-3,p型AlGaInP层的空穴浓度由6.0×10¹⁷cm^-3增大到1.1×10¹⁸cm^-3.但退火温度为780℃时,p型GaP层和p型AlGaInP层的空穴浓度分别下降至8×10¹⁷cm^-3和1.7×10¹⁷cm^-3,且Mg原子在AlGaInP系材料中的扩散加剧,导致未掺杂AlGaInP/GaInP多量子阱呈现p型电导.在460～700℃退火范围内,并没有使AlGaInP/GaInP多量子阱的发光性能发生明显变化.但退火温度为780℃时,AlGaInP/GaInP多量子阱的发光强度是退火前的2倍.     

高剂量离子注入形成的非晶层重新结晶过程中杂质外扩散的物理模型

本文提出了一个杂质沉淀引起位错生成、位错-杂质相互作用、杂质原子沿晶粒间界快速扩散的模型,用以解释高剂量离子注入形成的非晶层在重新结晶的退火过程中杂质外扩散和缺陷运动现象。给出了在位错的合应力场的影响下杂质的扩散方程。以能量为80keV,剂量为10¹⁶cm^-2的Pb⁺注入Si(111)面为例,对扩散方程进行了数学物理处理,从而给出了根据实验测量推演表观扩散系数随时间变化及位错的合应力场对杂质的作用力的纵向分布的方法。实验测得的位错合应力场对杂质的作用系数α≈8.4×10^-28dyn·cm³,退火时间在5×10³sec至8.25×10³sec内,表观扩散系数D随时间的变化为一指数关系。 关键词：     

注氮GaAs中的深能级及其对自由载流子的补偿

详细研究了注氮n型GaAs中深的和浅的杂质缺陷的电学性质。深能级瞬态谱(DLTS)技术测量表明,能量为140keV和剂量为1×10¹³cm^-2的氮离子注入并经800℃退火30min的GaAs中存在四个电子陷阱,E₁(0.111),E₂(0.234),E₃(0.415),E₄(0.669)和一个空穴陷阱H(0.545),而在能量为20keV和剂量为5×10^{14关键词：}     

钴离子注入对二氧化钛晶体的结构和光学性能的影响

采用离子注入法制备了钴离子掺杂的金红石相TiO₂样品;离子注入能量、注量分别为40 keV(1×10¹⁶cm^-2),80 keV(5×10¹⁵,1×10¹⁶,5×10¹⁶,1×10¹⁷cm^-2),120 keV(1×10¹⁶cm^-2). 通过XRD,XPS和UV-Vis等手段对掺杂前后样品的结构和光学性能进行了表征,分析了掺杂元素在金红石TiO₂中的存在形式. XRD测试表明随着注入能量的增加晶体的损伤程度增加. UV-Vis测试表明掺杂后所有样品在可见光区的吸收增强; 并且随着注量的增加,注量为5×10¹⁵cm^-2到5×10¹⁶cm^-2范围内注入样品的光学带隙逐渐变小. 关键词： 钴 二氧化钛 离子注入 掺杂     

离子注入Si损伤分布的光谱法多层分析

应用多层模型和最优化方法,由实验测得的离子注入Si的椭偏光谱以及单晶Si和离子注入非晶Si的光学常数,能分析离子注入Si的损伤分布。我们测量了2.1—4.6eV能量范围的椭偏光谱和光学常数,建立了多层计算模型和最优化方法。在模拟分析的基础上,计算了能量为40keV,剂量分别为4×10¹³和1.4×10¹⁴cm^-2的As⁺注入Si的损伤分布,并与背散射测量的结果比较。用多层模型和最优化方法也能从光谱分析其它物理量的分布,只要这些物理量对光学性质有显著的影响,并且在测量过程中不随光子能量而改变。 关键词：     

跳跃机构与低渗杂半导体杂质电导

在渗杂度很低时,由于少数杂质电离后引起场的起伏,电子在杂质上主要处于局域状态,电声子作用使电子能够在不同杂质上跳跃,但由于电子坐标算符与电声子作用交换,在电场中电子的运动实际上是一种击穿效应,而由声子束补偿能量。针对低补偿情况,略去复杂能带结构,我们由刘维方程出发,把密度矩阵对电场,然后对电声子作用展开,得到电流表达式及密度矩阵对角元所满足的玻茲曼型方程.只取到重迭积分二次项,我们得到了Miller等的网络方程,可以简单地求出平均阻抗,在低温极限下,得到σ～e^{(-βε_{(Be-1.54(rd/a)3/2))}}N_A^1/8,βε₃=βe²/(εr_d) -1.93(βE_A)^3/4。借助网络模型,我们分析了密度矩阵各部分的贡献,特别是与通常输运过程的差别。最后利用Anderson的结果,若K<10^-2,在对电导起主要作用的链上,在Ge,Si中浓度要在10¹⁴及10¹⁶cm^-3以下才能形成局域态,我们认为,考虑了电子间库仑作用后,载流子非局域并不与目前实验矛盾。 关键词：     

MW-ECR PE-UMS等离子体特性及对Zr-N薄膜结构性能的影响

采用静电探针技术对微波电子回旋共振(MW-ECR) 等离子体进行了诊断,利用等离子体增强 非平衡磁控溅射(PE-UMS)法在常温下制备了Zr-N薄膜, 通过EPMA，XRD，显微硬度对膜的 结构和性能进行评价.实验结果表明，随氮气流量增加，总的等离子体密度从807×10⁹c m^-3增加到831×10⁹cm^-3然后逐渐减小为752×10 ⁹cm^-3；而N₂⁺密度则从312×10^{8< /sup>cm-3线性递增到335×109cm-3；电子温度变化 不大.对薄膜而言，随N₂+密度增大，样品中氮含量增加，而晶粒逐 渐变小，当样品中N/ Zr原子比达到14时，薄膜中出现亚稳态的Zr₃N₄相以及非晶相， 在更高氮流量下，整 个薄膜转变为非晶态.与此相应，薄膜硬度由最初的225GPa增大到2678GPa 然后逐渐减 小到1982GPa. 关键词： 氮化锆薄膜 ECR等离子体 磁控溅射 诊断}     

Beryllium-hydrogen and zinc-hydrogen shallow acceptor complexes in germanium

New shallow acceptor complexes with hydrogenically-spaced excited states have been discovered in intentionally-doped crystals of otherwise ultra-pure germanium. The doping consists of >10¹⁴ cm⁻³ of group II impurities, and the crystals were grown under hydrogen atmosphere. The identification proposed in this paper is that of a hydrogen-group II impurity complex, with piezospectroscopic behavior of a 〈111〉-oriented defect.     

High resolution fourier transform spectroscopy of shallow acceptors in ultra-pure germanium

The excitation spectra of shallow acceptors in ultra-pure germanium (10⁹ cm^-3 < N_A ? N_D < 10¹² cm^-3 were studied using Fourier Transform Spectroscopy and photothermal excitation. Using samples with a total number of less than 10⁸ acceptor atoms, the signal to noise ratio was better than 100. In the purest samples the natural width of some excited states was found to be below the instrumental resolution of 0.03 meV (= 0.25 cm^-1). Some new observations involve the resolution of lines of states near the top of the valence band and the discovery of two unknown shallow acceptors.     

Magnetic moment relaxation of a shallow acceptor center in heavily doped silicon

Results of studying the temperature dependence of the residual polarization of negative muons in crystalline silicon with germanium (9×10 ¹⁹ cm ^?3 ) and boron (4.1×10 ¹⁸ , 1.34×10 ¹⁹ , and 4.9×10 ¹⁹ cm ^?3 ) impurities are presented. It is found that, similarly to n-and p-type silicon samples with impurity concentrations up to ～10 ¹⁷ cm ^?3 , the relaxation rate ν of the magnetic moment of a _μ Al acceptor in silicon with a high impurity concentration of germanium (9×10 ¹⁹ cm ^?3 ) depends on temperature as ν～T ^q , q≈3 at T=(5–30) K. An increase in the absolute value of the relaxation rate and a weakening of its temperature dependence are observed in samples of degenerate silicon in the given temperature range. Based on the experimental data obtained, the conclusion is made that the spin-exchange scattering of free charge carriers makes a significant contribution to the magnetic moment relaxation of a shallow acceptor center in degenerate silicon at T?30 K. Estimates are obtained for the effective cross section of the spin-exchange scattering of holes (σ _h ) and electrons (σ _e ) from an Al acceptor center in Si: σ _h ～10^?13 cm² and σ _e ～8×10^?15 cm² at the acceptor (donor) impurity concentration n _a (n _d )～4×10¹⁸ cm^?3.     

硅、锗中氧的低温红外吸收

在6—300K下,利用红外傅里叶光谱仪研究了400—4000cm^-1间的硅、锗中氧的红外吸收。采用高分辨条件时,分辨率可达0.5cm^-1。研究了在低温下利用硅的1106cm^-1吸收峰和锗的855cm^-1吸收峰探测硅和锗氧含量的探测限和误差。若样品厚度为2cm,估计在20K下,硅中氧含量探测限～9.6×10¹⁴氧原子·cm^-3,锗中氧含量探测限～3.0×10¹⁴氧原子·cm^-3。同时,对不同生长条件下直拉锗单晶的氧含量进行了研究,并与用锂沉淀法所求得的锗中氧含量加以比较。对不同氧含量的硅样品的1106cm^-1吸收峰在6—300K的变化进行了观察和讨论。 关键词：     

Electronic properties of hydrogen-related complexes in pure semiconductors

Hydrogen has been shown to activate the neutral impurities carbon, silicon and oxygen in ultra-pure germanium and form shallow level complexes. The double acceptors beryllium and zinc in silicon and germanium, as well as the triple acceptor copper in germanium, can be partially passivated, leading to single hole acceptors. The study of the electronic level spectrum of the single carrier bound to these centers at low temperatures has provided much information on symmetry and composition. Most centers reveal a symmetry axis along [1 1 1] and are static. In some cases hydrogen has been found to tunnel between equivalent real space positions. hoto hermal onization pectroscopy (PTIS) has been the most important tool for the study of the optical transitions of the hole (electron) in these hydrogen containing complexes. This photoconductivity technique combines high sensitivity with high resolution and permits the study of shallow acceptors or donors present at concentrations as low as 10⁸ cm^-3. Even lower limits may be attained under favorable circumstances.     

硅的低温电学性质

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。     

Lattice disorder in germanium by boron ion bombardment

Abstract

The lattice disorder produced in germanium by 56keV boron-ion bombardment has been measured using the channeling-effect technique. The dependence on dose (10¹⁴-10¹⁶ ions/cm²) and implantation temperature (?90 °C to +130°C) has been studied. It is found that at room-temperature, each incident boron ion creates ?10 times more disorder in germanium than in silicon. It is remarked that, contrary to the present results, previously established anneal stages generally occur at significantly lower temperatures in germanium than in silicon.     

DLTS and PTIS of new donors in oxygen-doped germanium

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: E_c?E_II = 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.     

The effect of uniaxial static pressure on the behavior of an aluminum acceptor impurity in silicon

The effect of uniaxial compression on the behavior of shallow aluminum acceptor centers in silicon has been studied. The _μAl impurity atoms were created by implanting negative muons into silicon single crystals doped with phosphorus to 1.6×10¹³ cm^?3 (sample 1) and 1.9×10¹³ cm^?3 (sample 2). The muon polarization was studied in the temperature range 10–300 K. Measurements were performed in a magnetic field of 2.5 kG oriented perpendicularly to the muon spin. The samples were oriented so that the selected crystal axis ([111] and [100] in samples 1 and 2, respectively), the magnetic field, and the initial muon-spin polarization were mutually perpendicular. External pressure applied to the sample along the indicated crystal axis changed both the absolute value of the acceptor magnetic-moment relaxation rate and the character of its temperature dependence.     

High resolution photoconductivity studies of residual shallow donors in ultrapure Ge

High resolution photoconductivity studies of residual shallow donors in ultrapure (n = 2 x 10¹⁰cm^-3) germanium have revealed absorption corresponding to transitions to higher lying levels not previously observed because of spectrometer limitations and/or line broadening due to impurity-impurity interactions. In this paper we list the results of our studies of four residual donors in high purity material, compare these results with a theoretical calculation for higher lying energy level spacings, and examine the temperature dependence of the two step photothermal photoconductivity process.