GaAs／AlxGa1—xAs多量子阱红外探测器的光调制光谱研究

运用光调制光谱方法测量了ＧａＡｓ／ＡｌｘＧａ１－ｘＡｓ多量子阱红外探测器材料的调制反射谱，结果表明光调制光谱可以精确确定阱宽、Ａｌ组分、子带跃迁能量和探测峰值波长等许多重要参数。结合实验结果，采用Ｋｒｏｎｉｇ－Ｐｅｎｎｙ模型对材料能带结构进行了理论计算，与实验结果相符。     

新的空间调制光谱技术在半导体超晶格量子阱中的应用

报道一种通过转动样品来实现空间调制微分反射（ＤＲ）光谱技术,给出ＧａＡｓ／ＡｌＧａＡｓ多量子阱和应变ＩｎＧａＡｓ／ＧａＡｓ多量子阱在室温下的ＤＲ谱实验测量结果,并与光调制反射谱（ＰＲ）实验和理论计算结果相比较．实验证明ＤＲ谱的信号比ＰＲ谱更强,可达１０－２量级,两者一致并与理论计算结果符合得很好．ＤＲ谱是研究薄膜和微结构的有效方法     

GaAs/AlGaAs量子阱空间差分光调制反射光谱研究

本文报道了空间差分光调制反射光谱,指出了它与常规光调制反射谱的区别,与常规光调制反射光谱相比较,它具有更好的信噪比和灵敏度。利用该光谱方法对ＧａＡｓ／ＡｌＧａＡｓ量子阱的实验测量结果表明,空间差分光调制反射光谱具有丰富的光谱结构。     

InGaAs／GaAs和InGaAs／AlGaAs应变层量子阱中的子带弛豫过程

利用时间光辨光谱技术，在１１￣９０Ｋ温度范围研究了不同阱宽的ＩｎＧａＡｓ／ＧａＡｓ和ＩｎＧａＡｓ／ＡｌＧａＡｓ应变层量子阱子带弛豫过程，讨论了这两种量子阱材料中不同散射机制的作用。     

LP－MOCVD生长InGaAs／GaAs量子阱

用低压ＭＯＣＶＤ（ＬＰ－ＭＯＣＶＤ）生长三种不同的ＩｎＧａＡｓ／ＧａＡｓ应变层量子阱材料，其中两种含ＡｌＧａＡｓ限制层。结果表明，ＡｌＧａＡｓ限制层对量子阱的发光强度影响很大，与没有ＡｌＧａＡｓ限制层的结果相比，带ＡｌＧａＡｓ限制层的结构的发光强度要强一个数量级以上。在低温（１８Ｋ）ＰＬ光谱图中，我们看到，除了存在主峰以外，在主峰两侧还各有一个子峰，这些子峰可能与量子阱的质量有关。     

应变In0.20 Ga0.80As／GaAs单量子阱结构的光谱研究

报道了用光致发光光谱，吸收光谱和光电流谱研究具有相同组伊阱宽，不同覆盖层厚度的应变Ｉｎ０．２０Ｇａ０．８０Ａｓ／ＧａＡｓ单量子阱结构的实验结果，结果理论计算，观察到ＧａＡｓ覆盖层厚度对单量子阱结构的材料质量，应力驰豫和发光淬灭机制的影响，确定了各样品应变值和导带不连续因子Ｑｃ，并讨论了这种结构发光机制。     

GaAlAs／GaAs量子阱LD泵浦Nd：YAG激光器

利用分子束外延技术生长出了ＧａＡｌＡｓ／ＧａＡｓ折射率渐变分别限制单量阱材料。用该材料作出的激光二极管作泵浦源对Ｎｄ：ＹＡＧ激光器进行端面泵浦实验，在工作电流为３．３Ａ时，ＬＤ输出功率为２．７Ｗ，得到Ｎｄ：ＹＡＧ激光器的输出功率达７００ｍＷ，光－光转换效率达２０％。     

GaAs／AlGaAs分子束外延量子阱材料的研究

采用进口分子束外延设备生长了ＧａＡｓ／ＡｌＧａＡｓ单量子阱和多量子阱材料。在理论分析和实验总结的基础上，对材料结构进行了优化，增加了ＧａＡｓ／ＡｌＧａＡｓ超晶格缓冲层来进行缺陷抑制，并在外延时精确地控制生长，这样获得的量子阱材料通过Ｘ射线双晶衍射和Ｃ－Ｖ测量表明：得到的材料性能良，为新型光电器件的制作和进一步的材料研究打下了基础。     

分子束外延GaAs／AlGaAs超晶格缓冲层量子阱材料的研究

采用分子束外延技术生长了ＧａＡｓ／ＡｌＧａＡｓ单量子阱得多量子阱材料。采用ＧａＡｓ／ＡｌＧａＡｓ超晶格缓冲层掩埋衬底缺陷，获得的量子阱结构材料被成功地用于制作量子阱激光器。波长为７７８ｎｍ的激光器，最低阈值电流为３０ｍＡ，室温下线性光功率大于２０ｍＷ。     

应变单量子阱InGaAs／GaAs的光谱研究

应变单量子阱ＩｎＧａＡｓ／ＧａＡｓ的光谱研究沈文忠，唐文国，沈学础（中国科学院上海技术物理研究所，红外物理国家重点实验室，上海２０００８３）近来，人们对ＩｎｘＧａ１－ｘＡｓ／ＧａＡｓ应变超晶格和量子阱结构产生了浓厚的兴趣是基于高速器件设计的需要。随着...     

Near-Infrared Absorption in Lattice-Matched AlInN/GaN and Strained AlGaN/GaN Heterostructures Grown by MBE on Low-Defect GaN Substrates

We have investigated near-infrared absorption and photocurrent in lattice-matched AlInN/GaN and strained AlGaN/GaN heterostructures grown by molecular-beam epitaxy (MBE) on low-defect GaN substrates for infrared device applications. The AlGaN/GaN heterostructures were grown under Ga-rich conditions at 745°C. Material characterization via atomic force microscopy and high-resolution x-ray diffraction indicates that the AlGaN/GaN heterostructures have smooth and well-defined interfaces. A minimum full-width at half-maximum of 92 meV was obtained for the width of the intersubband absorption peak at 675 meV of a 13.7 Å GaN/27.5 Å Al_0.47Ga_0.53N superlattice. The variation of the intersubband absorption energy across a 1 cm × 1 cm wafer was ±1%. An AlGaN/GaN-based electromodulated absorption device and a quantum well infrared detector were also fabricated. Using electromodulated absorption spectroscopy, the full-width at half-maximum of the absorption peak was reduced by 33% compared with the direct absorption measurement. This demonstrates the suitability of the electromodulated absorption technique for determining the intrinsic width of intersubband transitions. The detector displayed a peak responsivity of 195 μA/W at 614 meV (2.02 μm) without bias. Optimal MBE growth conditions for lattice-matched AlInN on low-defect GaN substrates were also studied as a function of total metal flux and growth temperature. A maximum growth rate of 3.8 nm/min was achieved while maintaining a high level of material quality. Intersubband absorption in AlInN/GaN superlattices was observed at 430 meV with full-width at half-maximum of 142 meV. Theoretical calculations of the intersubband absorption energies were found to be in agreement with the experimental results for both AlGaN/GaN and AlInN/GaN heterostructures.     

Potential difference and photovoltaic effect arising from distortion of the electron wave function in a GaAs quantum well with a thin AlGaAs barrier

This paper discusses changes in the spectrum and distortion of the electron wave function of a GaAs quantum well when a thin AlGaAs barrier is introduced into it. The potential difference generated across the quantum well by distortion of the electron wave function is calculated, along with its dependence on the position of the barrier in the quantum well. The photovoltaic response of the structure to optical intersubband excitations is also calculated, along with the role of wave function and electronic spectrum distortion as well as intersubband nonradiative transitions in generating this response. The suitability of a GaAs quantum well with a thin barrier for use as an infrared detector is considered. Fiz. Tekh. Poluprovodn. 32, 1246–1250 (October 1998)     

n型半导体量子阱红外探测器的正入射吸收机制

基于有效质量理论，从导带子带间光跃迁矩阵元的表达式出发，推出ｎ型半导体量子陆红外探测器的正入射吸收条件，用一些简单的数学手段，把正入射的吸收系数表达为量子阱生长方向的解析函数，进而讨论正入射吸收的优化、极限及与平行吸收的比较。     

In_（0．2）Ga_（0．8）As／GaAs应变多量子阱结构的光调制反射和热调制反射谱的研究

对Ｉｎ（０．２）Ｇａ（０．８）Ａｓ／ＧａＡｓ应变多量子阱在７７Ｋ下的光调制反射谱（ＰＲ）和热调制反射谱（ＴＲ）进行了实验研究．对ＰＲ结果的线形拟合指认了应变多量子阱中子能级的跃迁，并与理论计算结果作了比较．实验对比确认ＰＲ中１１Ｈ、１３Ｈ等跃迁结构为非耦合态、具有电场调制机构的一阶微商性质．而１１Ｌ、３１Ｈ、２２Ｈ等跃迁结构为阶间耦合态，对这些隧穿耦合的低场调制产生三阶微商特性．     

The effect of resonant sublevel coupling on intersubband transitions in coupled double quantum wells

The effect of resonant sublevel coupling on intersubband transitions in double quantum wells is investigated using far-infrared spectroscopy. We study widely tuneable parabolic double quantum wells in which potential spikes of different energetic height and thickness provide tunnel barriers for the electron systems on either side of the barrier. The use of gate electrodes enables us to tune both the carrier densities as well as the respective sublevel spacings and allow for a manifold degeneracy scheme like in an artificial molecule where the atomic number of both partners can be intentionally changed. Depending on the actual experimental condition, we observe pronounced level anticrossings into a symmetric and antisymmetric state. This single-particle sublevel coupling manifests itself in a rich spectrum of the observed collective intersubband transitions which occur at the depolarization shifted intersubband energy.     

Photoreflectance characterization of semiconductors and semiconductor heterostructures

The electromodulation method of photoreflectance (PR) is becoming an important tool for the characterization of semiconductors, semiconductor interfaces and semiconductor microstructures such as superlattices, quantum wells, multiple quantum wells and heterojunctions. Since PR is contactless, requires no special mounting of the sample and can be performed in a variety of transparent ambients it can be utilized for in-situ monitoring of growth at elevated temperatures, in-situ elevation at 300K before the samples are removed from the growth/processing chamber as well as convenient ex-situ characterization. This invited article discusses some recent uses of PR to measure (a) the direct gap (and spin-orbit split component) of InP up to 600° C, (b) strains in Si at the Si/SiO₂ interface, (c) changes in the surface Fermi level of GaAs caused by photowashing, (d) quantized intersubband transitions in a GaAs/Gao_0.82Al_0.18As multiple quantum well and (e) two-dimensional electron gas effects in selectively dopedn-Ga_o.7Al_o.3As/ GaAs heterostructures.     

GaN基多量子阱红外探测器研究进展（特邀）

多量子阱红外探测器是一种新型的利用子带跃迁机制的探测器件,具有非常高的设计自由度。GaN/Al(Ga)N量子阱由于大的导带带阶,超快的电子驰豫时间,超宽的红外透明区域以及高的声子能量,使得其成为继GaAs量子阱红外探测器之后又一潜在的探测材料结构。文中详细综述了国内外关于GaN基量子阱红外子带吸收及其探测器件的研究进展。首先介绍了量子阱红外探测器的工作原理及其选择定则,接着从极性GaN基多量子阱、非极性或半极性GaN基多量子阱以及纳米线结构GaN基多量子阱三个方面回顾当前GaN基多量子阱红外吸收的一些重要研究进展,包括了从近红外到远红外甚至太赫兹波段范围的各种突破。最后回顾了GaN基多量子阱红外探测器件的研究进展,包括其光电响应特性和高频响应特性,并对其未来的发展进行总结和展望。     

量子阱太赫兹探测材料设计与生长的研究*

子带跃迁的量子阱结构太赫兹探测器具有响应速度快等特点,有广泛的应用前景,越来越受到研究 人员的关注。以量子力学基本原理,量子阱结构材料光吸收的特性,以及光导型探测器暗电流分析为基础,进行了 量子阱厚度、势垒层Al 含量和量子阱掺杂浓度等参数的AlGaAs/ GaAs 量子阱太赫兹探测材料结构设计,按照优化 后的外延参数进行了材料生长,获得了符合设计要求的探测材料。     

Calculation of linear and nonlinear intersubband optical absorptions in a quantum well model with an applied electric field

Analytic forms of the linear and the third-order nonlinear optical intersubband absorption coefficients are obtained for general asymmetric quantum well systems using the density matrix formalism, taking into account the intrasubband relaxation. Based on this model, we calculate the electric field dependence of the linear and the third-order nonlinear intersubband optical absorption coefficients of a semiconductor quantum well. The energy of the peak optical intersubband absorption is around 100 meV (wavelength is 12.4 μm). Thus, electrooptical modulators and photodetectors in the infrared regime can be built based on the physical mechanisms discussed here. The contributors to the nonlinear absorption coefficient due to the electric field include 1) the matrix element variation and 2) the energy shifts. Numerical results are illustrated.     

In0.15Ga0.85As／GaAs多量子阱子能带跃迁压力效应

用光调制吸收光谱方法在不同压力条件下研究了In_(0.15)Ga_(0.85)As/GaAs应变多量子阱的子能带跃迁,发现子能带跃迁能量随压力的变化行为与构成量子阱的组成体材料带间跃迁能量的变化相似,并且子能带跃迁能量压力系数与量子阱的宽度有关。还讨论了压力可能引起的导带不连续率的变化和In_(0.15) Ga_(0.85)As应变层的临界厚度。