ELECTROLUMINESCENCE SPECTRA OF GexSi1-x/Si SINGLE QUANTUM WELL

The electroluminescence of Ge_xSi_1-x/Si single quantum well was measured at temper-atures above room temperature along the growth direction and the direction normal to it. TO and NP peaks were resolved.     

ELECTROREFLECTANCE SPECTRA OF GexSi1-x/Si STRAINED LAYER MULTIPLE-QUANTUM WELLS

We have investigated the optical transitions above the fundamental gap of a set of Ge_xSi_1-x/Si strained layer multiple-quantum wells by electroreflectance (ER). The sam-ples were grown by molecular beam espitaxy (MBE). The thickness of the strained layer of Ge_xSi_1-x was 5nm with Ge concentration x in the range from 0.4 to 0.5, and the Si barrier layer greater than 16nm. Considering the energy shift caused by strain and quantum well confinement, we were able to clearly recognize the transitions from different quantum well structures associated with the critical points E₀, E′₀, and E₁. The transitions of the critical points E₀ and E′₀, which are very weak in bulk mateials, are apparently enhanced in the quantum well structures.     

SiGe/Si量子阱的低温光荧光和电注入发光

使用Si-MBE生长了阶梯形折射率分布SiGe/Si量子阱材料,在低温下观测到无声子参与的光荧光和电注入发光。阶梯形折射率分布SiGe/Si电子阱结构有利于提高发光效率。讨论了这种结构的光学和电学特性。     

单频导纳谱法测量锗硅量子阱的能带偏移

提出了用单频导纳谱法测量储硅单量子阶的能带偏移，与常规的多频导纳谱相比，它只需测一个频率的导纳谱就能得到更精确的实验结果。用该方法对Ｓｉ／Ｇｅ_０．３３Ｓｉ_０．６７／Ｓｉ单量子阱进行测试，得到激活能为Ｅ_a＝０．２０ｅＶ。为了计算出能带偏移值，必须能准确确定具有单量子阱结构样品中的费密能级位置，由于在单量子阱结构中费密能级的位置与阱材料、垒材料的掺杂浓度、阱的高度（即能带偏移）及温度等几个因素均有关。为此，本文通过解泊松方程，计算出结合本文样品 关键词：     

在ZnSxSe1-x单晶中自由激子光谱的研究

在高纯ZnSxSe1-x单晶的自由激子激发光谱中首次观察到过热激子能量弛豫的振荡结构.激发光谱的结构,激子的寿命与ZnSxSe1-x三元系的组分x密切有关.x=0.125和x=0.02样品相比较,随着X的增加而增加自由激子的发光效率,同时在激发光谱的振荡结构中增加光滑成分和背景,亦即减少光学声子形式的能量弛豫,增加声学声子形式的能量弛豫.这些现象归结于在混晶中非均匀势垒引起的激子迁移率的减小.     

浅ZnCdSe/ZnSe量子阱的光泵受激发射

本文主要研究浅ZnCdSe/ZnSe单量子阱在77K温度下的光致发光。在不同激发密度下,讨论了该结构的发光机制,把77K温度下的受激发射归结为是激子-激子散射所引起的。文中还分析了在浅ZnCdSe/ZnSe量子阱中能够实现与激子相关的受激发射的原因。     

RAMAN SCATTERING INTENSITIES OF FOLDED LONGITUDINAL ACOUSTIC PHONONS IN GexSi1-x/Si SUPERLATTICES

In terms of photoelastic mechanism we have investigated the Raman scattering intensities of the folded longitudinal acoustic (FLA) phonons in Ge_xSi_1-x/ Si superlattices (SLs), taking into account the differences between the acoustic and photoelastic parameters of the two constituents in the SLs. The relative intensities calculated for the FLA phonons are in excellent agreement with the experimental results at the frequencies up to about 50 cm^-1. The broadening of the linewidth arising from the so called strong acoustic attenuation, which was reported previously located around the frequency 15 cm^-1 in Ge_xSi_1-x/Si SLs(x≈0.5), has not been observed in this work.     

ORDER ALLOY IN GexSi1-x/Si(100) STRAINED-LAYER SUPERLATFICES

The Ge_xSi_1-x/Si(100) strained-layer superlattices have been investigated by means of the transmission electron microscopy of the cross-sectional specimen (XTEM) and the high resolution electron microscopy (HREM), The order alloy with a period of modulation twice as large as the lattice constant along <100> zone axis has been found in the alloy layers of the superlattices with x≈0.4-0.5. This order struc-ture makes the superlattices inhomogeneously strained. The result of the compuler simulation shows that the order alloy exhibits an altemating stack of 2 monolayers of Ge atoms and 2 monolayers of Si atoms along the <100> zone axis. Thc calculated elastic strain energy of the disorder alloy reported in the litera-ture is very close to that of the order alloy along <100> zone axis. Thus, during the MBE growth of the alloy layers, both the disorder and order alloys can be formed along <100> zone axis.     

InGaAsP/InGaP/GaAs单量子阱激光器工作特性

利用低压-金属有机化学汽相沉积(LP-MOCVD)方法研制出InGaAsP/InGaP/GaAs单量子阱大功率激光器并分析了阈值电流密度、特征温度和外微分量子效率与腔长的关系.     

ABNORMAL ENERGY DEPENDENCE OF AXIAL MINIMUM CHANNELING YIELDS IN GexSi1-x/Si(100) STRAINED

An energy dependence of the axial minimum channeling yield in Ge_xSi_1-x/Si(100) Strained-layer superlattice is observed in the energy range of impinging He⁺ ione from 1.2 to 3.0 MeV. For [100] axial channeling, the measurements ere in agreement with what have been known in a single crystal. However, for [110] axial channeling, it is found that the minimum channeling yields increase markedly with the increase of He⁺ ion energy, which is contrary to the general channeling behaviors in a single crystal. A tentative model is suggested to explain this aberrance.     

AlyGa1-yAs/AlxGa1-xAs量子阱激光器材料的光致荧光谱

测量了Al_yGa_1-yAs/Al_xGa_1-xAs量子阱激光材料的光致荧光谱.发现在室温连续激光器材料的光致荧光谱中有两个峰,而不能激射的材料中则只有一个很宽的峰.将高能峰归属于准费密能级电子的跃迁. 关键词：     

Nonparabolicity corrections to the valence band energy levels of Si/GexSi1-x quantum wells

In earlier work, subband energies of Si/Ge_xSi_1-x quantum wells were obtained neglecting valence band nonparabolicity. Here we present an algorithm for solving for the energies and wavefunctions of the mixed light-hole and split-off subbands under stress, which incorporates the energy dependence of the effective mass exactly. We show that this gives corrections to the energies that are of the order of tens of meV, and results in small nonorthogonality corrections to the envelope wavefunctions. These corrections are discussed for several cases of physical interest and are compared to the results obtained assuming a constant bandedge effective mass.     

ELECTRO-LUMINESCENCE AND PHOTO-LUMINESCENCE FROM STRAINED SiGe/Si QUANTUM WELL

Photo-luminescence and electro-luminescence from step-graded index SiGe/Si quantum well grown by molecular beam epitaxy is reported. The SiGe/Si step-graded index quantum well structure is beneficial to the enhancing of electro-luminescence. The optical and electrical properties of this structure are discussed.     

低温下ZnSe－ZnS多量子阱的光致发光光谱和喇曼散射谱

本文报导了２Ｋ下，在ＧａＡｓ（１００）衬底上用ＭＯＣＶＤ方法生长的ＺｎＳｅ－ＺｎＳ多量子阱材料的光致发光光谱和喇曼散射谱．用共振激发、共振喇曼和共振瑞利散射等方法对各发光谱带和喇曼散射峰的来源和机制进行了鉴别．     

低温下ZnSe-ZnS多量子阱的光致发光光谱和喇曼散射谱

本文报导了2K下,在GaAs(100)衬底上用MOCVD方法生长的ZnSe-ZnS多量子阱材料的光致发光光谱和喇曼散射谱.用共振激发、共振喇曼和共振瑞利散射等方法对各发光谱带和喇曼散射峰的来源和机制进行了鉴别.     

电场调制下单量子阱ZnCdSe／ZnSe的激射行为研究

近年来,随着宽禁带Ⅱ－Ⅵ族半导体激光器取得突破性进展［１］,对ＺｎＳｅ基超晶格与量子阱的受激发射也进行了广泛的研究［２,３］,同时对电场调制下的ＺｎＳｅ基超晶格的受激发射也有过报导［４］．但对于电场调制下的ＺｎＣｄＳｅ／ＺｎＳｅ基单量子阱的激射行为研...     

Si_（1－x）Ge_x／Si量子阱发光材料的分子束外延生长及其结构研究

采用固源Ｓｉ分子束外延，在较高的生长温度于Ｓｉ（１００）衬底上制备出Ｓｉ１－ｘＧｅｘ／Ｓｉ量子阱发光材料．发光样品的质量和特性通过卢瑟福背散射、Ｘ射线双晶衍射及光致发光评估．背散射实验中观察到应变超晶格的反常沟道效应；Ｘ射线分析表明材料的生长是共度的、无应力释放的，结晶完整性好．低温光致发光主要是外延合金量子阱中带边激子的无声发射和横光学声子参与的激子复合．并讨论了生长温度对量于阱发光的影响．     

用深能级瞬态谱方法研究赝晶Si/Ge0.25Si0.75/Si单量子阱的价带偏移

应变的Ge_xSi_1-x层和未应变的硅层间的能带偏移主要是价带偏移。量子阱中载流子的热发射能与界面的能带偏移有着密切的关系。本文用深能级瞬态谱(DLTS)研究分子束外延生长的p型Si/Ge_0.25Si_0.75/Si单量子阱的价带偏移,阱宽为15nm,考虑到电场的影响和量子阱中第一子能级的位置,对从DLTS得到的热发射能进行适当的修正,可以计算出Si/Ge_0.25Si_0.75/S 关键词：     

CdxZn1-xS:SmF3的红色薄膜电致发光

本文首次报道了用CdxZn1-xS替代ZnS作为基质,改进SmF3的TFEL的实验;通过适当地在基质中掺杂CdS,在一定程度上提高了SmF3的TFEL发光亮度;分析了CdxZn1-xS基质中Cd含量对SmF3的TFEL的影响,探讨了发光亮度提高的原因.