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：     

应力导致InAs/In0.15Ga0.85As量子点结构中In0.15Ga0.85As阱层的合金分解效应研究

利用固源分子束外延技术，在In_0.15Ga_0.85As/GaAs量子阱生长了两个InAs/In_0.15Ga_0.85As量子点(DWELL)样品.通过改变其中一个InAs DWELL样品中的In_0.15Ga_0.85As阱层的厚度和生长温度，获得了量子点尺寸增大而且尺寸分布更均匀的结果.结合光致发光光谱(PL)和压电调制光谱(PzR)实验结果，发现该样品量子点的光学性质也同时得到 关键词： 合金分解效应 0.15Ga_0.85As量子点')" href="#">InAs/In_0.15Ga_0.85As量子点 光致发光光谱 压电调制光谱     

两个子带占据的In0.53Ga0.47As/In0.52Al0.48As量子阱中填充因子的变化规律

研究了低温(15K)和强磁场(0—13T)条件下, InP基In_053Ga_047As/In_052Al_048As量子阱中电子占据两个子带时填充因子随磁场的变化规律.结果表明,在电子自旋分裂能远小于朗道能级展宽的情况下,如果两个子带分裂能是朗道分裂能的整数倍时,即ΔE₂₁=kω_c(其中k为整数),填充因子为偶数;当两个子带分裂能为朗道分裂能的半奇数倍时,即ΔE₂₁=(2k+1)ω_c/2,填充因子出现奇数. 关键词： 053Ga_047As/In_052Al_048As量子阱')" href="#">In_053Ga_047As/In_052Al_048As量子阱 填充因子 磁输运     

用光伏谱方法研究InGaAs/GaAs应变量子阱的性质

采用低温光伏谱方法，研究了应变In_0.18Ga_0.82/GaAs单量子阱结构中各子能级之间的光跃迁，并与理论计算的结果进行比较，对光伏谱的谱峰跃迁能量随温度变化的分析，表明量子阱中的应变与温度基本无关．研究了光伏谱的谱峰半高宽度随温度的变化关系．讨论了声子关联、混晶组分起伏及生长界面不平整对光伏谱谱峰宽度的影响 关键词：     

赝配GaAs/In0.2Ga0.8As量子阱导带不连续量的C-V和电容瞬态测量

分别采用二种不同方法测量分子束外延(MBE)生长GaAs/In_0.2Ga_0.8As单量子阱结构的导带不连续量ΔE_c:1) 考虑样品界面电荷修正的电容-电压(C-V)分布；2) 量子阱载流子热发射产生的电容瞬态(DLTS).C-V测得的ΔE_c=0.227eV,大约相当于89% ΔE_g.DLTS测得的ΔE_c=0.229eV,大约相当于89.9% ΔE_g.结果 关键词：     

调制掺杂的应变In0.60Ga0.40As/In0.52Al0.48As多量子阱结构的光致发光谱研究

报道了调制掺杂的应变In_0.60Ga_0.40As/In_0.52Al_0.48As多量子阱中室温光致发光光谱.观察到n=1和2电子子带到n=1重空穴子带的强发光峰.在低温下可以观察到n=1电子子带到n=1轻空穴弱发光肩胛.通过对发光强度随激发功率及温度依赖关系以及理论模型的分析研究,认为该调制掺杂量子阱中辐射复合效率降低的主要机制是应变失配位错对载流子的陷阱作用.界面上的失配位错是陷阱的主要来源.并用静态的光致发光理论模型 关键词：     

双δ掺杂In0.65Ga0.35As/In0.52Al0.48As赝型高迁移率晶体管材料子带电子特性研究

研究了基于InP基的In_0.65Ga_0.35As/In_0.52Al_0.48As赝型高迁移率晶体管材料中纵向磁电阻的Shubnikov-de Haas(SdH)振荡效应和霍耳效应，通过对纵向磁电阻SdH振荡的快速傅里叶变换分析，获得了各子带电子的浓度，并因此求得了各子带能级相对于费米能级的位置.联立求解Schrdinger方程和Poisson方程，自洽计算了样品的导带形状、载流子浓度分布以及各子带能级和费米能级位置.理论计算和实验结果很好符合.实验和理论计算均表明，势垒层的掺杂电子几乎全部转移到了量子阱中，转移率在95%以上. 关键词： SdH振荡 二维电子气 FFT分析 自洽计算     

AlxGa1-xN/GaN双量子阱的结构和掺杂浓度对子带间跃迁波长和吸收系数的影响

用薛定谔方程和泊松方程自洽计算的方法研究了Al_0.75Ga_0.25N/GaN对称双量子阱(DQWs)中子带间跃迁(ISBT)的波长和吸收系数对中间耦合势垒高度、中间耦合势垒宽度、势阱宽度和势垒掺杂浓度的依赖关系.研究发现,第一奇序子带S_1ood与第二偶序子带S_2even ISBT波长随着中间耦合势垒高度的降低而变短.当中间耦合势垒高度高于0.62 eV时,S_{1odd< 关键词： 自洽 x}Ga_1-xN/GaN双量子阱')" href="#">Al_xGa_1-xN/GaN双量子阱 子带间跃迁     

852 nm半导体激光器InGaAlAs、InGaAsP、 InGaAs和GaAs量子阱的温度稳定性

为了提高852 nm半导体激光器的温度稳定性,理论计算了InGaAlAs、InGaAsP、InGaAs和GaAs量子阱的增益,模拟对比并研究了不同量子阱的增益峰值和峰值波长随温度的漂移。结果显示,采用In_0.15Ga_0.74-Al_0.11As作为852 nm半导体激光器的量子阱可以使器件同时具有较高的增益峰值和良好的温度稳定性。使用金属有机化学气相沉积(MOCVD)外延生长了压应变In_0.15Ga_0.74Al_0.11As单量子阱852 nm半导体激光器,实验测得波长随温度漂移的数值为0.256 nm/K,实验测试结果验证了理论计算结果。     

张应变In1-xGaxAsyP1-y/InP材料光致荧光谱温度特性的测试与分析

报道了具有2，3个量子阱的In_1-x1Ga_x1As_y1P_1-y1/In_1-x2Ga_x2As_y2P_1-y2/InP张应变量子阱材料的光致荧光谱和X射线双晶衍射摇 关键词：     

Electromodulation spectroscopy of In0.53Ga0.47As/In0.53Ga0.23Al0.24As quantum wells

In_0.53Ga_0.47As/In_0.53Ga_0.23Al_0.24As quantum wells (QWs) of various widths have been grown by molecular beam epitaxy on the InP substrate and investigated by electromodulation spectroscopy, i.e. photoreflectance (PR) and contactless electroreflectance (CER). The optical transitions related to the QW barrier and the QW ground and excited states have been clearly observed in PR and CER spectra. The experimental QW transition energies have been compared with theoretical predictions based on an effective mass formalism model. A good agreement between experimental data and theoretical calculations has been observed when the conduction band offset for the In_0.53Ga_0.47As/In_0.53Ga_0.23Al_0.24As interface equals 60%. In addition, it has been concluded that the conduction band offset for the In_0.53Ga_0.23Al_0.24As/InP interface is close to zero. The obtained results show that InGa(Al)As alloys are very promising materials in the band gap engineering for structures grown on InP substrate.     

Band offsets in In0.15Ga0.85As/ GaAs and In0.15Ga0.85As/Al0.15Ga0.85As studied by photoluminescence and cathodoluminescence

Photoluminescence and cathodoluminescence measurements of strained undoped In_0.15Ga_0.85As/GaAs and In_0.15Ga_0.85As/Al_0.15Ga_0.85As quantum well structures with emission lines attributed to the first electron–first heavy hole and first electron–first light hole excitonic transitions have been analysed theoretically within the eight-band effective mass approximation. For In_0.15Ga_0.85As/GaAs the results are consistent with either type I or type II alignment of the light hole band. In the case of In_0.15Ga_0.85As/Al_0.15Ga_0.85As our results indicate type II alignment for the light hole band and offset ratio ofQ = 0.83.     

In0.15Ga0.85As—GaAs应力层多量子阱中束缚子带—连续带跃迁

在10—300K温度范围,研究了稳态发光二极管(LED)辐照对15周期的In_0.15Ga_0.85As(8nm)-CaAs(15nm)应力层多量子阱的光电流谱的影响。各跃迁过程对应的光电流峰的强度随LED光强的增大而减弱,并且具有不同的变化规律。据此可区分出束缚子带和连续带间的跃迁及其亚结构,并由跃迁的能量位置,直接确定导带和价带的不连续量,得出重空穴价带的能带台阶Q_v=0.38±0.01。 关键词：     

Photoluminescence of InGaAs/GaAs strained-layer quantum well structures under high pressure

Abstract

Measurements of the photoluminescence (PL) of strained In_0.2Ga_0.8As/GaAs and In_0.15Ga_0.85As/GaAs quantum well structures together with the PL from bulk GaAs, in a diamond anvil cell show that the pressure coefficient of the ground confined state in the wells depends upon well width (L_Z). In the thinnest wells, the coefficient is closer to that of the bulk GaAs (10.7 meV/kbar), as expected. However, in the widest wells the coefficients tend to values (9.5meV/kbar for the 15% alloy and 9.1meV/kbar for the 20% alloy) that are significantly lower than the pressure coefficient of unstrained In_0.53Ga_0.47As (10.9meV/kbar). It is found that the low pressure coefficients can not be explained by the change in uniaxial stress with pressure due to a difference in bulk moduli between the barrier and well.     

Stokes shift in one-side modulation-n-doped-strained GaxIn1 − xAs/InP asymmetric quantum well

The effects of strain on the Stokes shift in one-side modulation-dopedGa_xIn_1 − xAs /InP asymmetric quantum wells (AQWs) are systematically investigated. By making use of a self-consistent Poisson–Schrödinger solver in the frame of a finite difference method, the quasi-Fermi levels and the band bending are determined under the effective mass approximation. The central-zone valence-band structures for compressively strained and tensile strained AQWs were calculated by making use of a four-band Luttinger–Kohn Hamiltonian. It was found that the strain influences the relative positions of the heavy-hole HH₁and the light-hole LH₁subbands and that the Stokes shifts are greatly reduced by tensile strain in the case of a Ga_0.6In_0.4As /InP AQW. Moreover, it was found that due to the presence of the two-dimensional electron gas the Stokes shifts in AQWs are much larger than the corresponding ones for a square quantum well. Also, the variation of the Stokes shift with spacer layer width for compressively strained AQWs was found to be more rapid than that for tensile strained AQWs.     

Observation of confined states in anIn0.53Ga0.47As/In0.52Al0.48Asmulti-quantum wells structure by quantum confined Stark effects

Photocurrent spectra in an In_0.53Ga_0.47As /In_0.52Al_0.48As multi-quantum wells structure containing 9.4 nm wide wells were measured at room temperature in electric fields. The exciton peaks of ground-state transitions shifted fairly in 167 kV cm ^− 1as the quantum confined Stark effect. Stark shifts were calculated by using the Runge–Kutta method using the effective mass equation with our experimental band parameters. Our parameters are the hole effective masses and valence band offset derived from saturation of a highest eigen energy, electron effective mass depending on energies and the conduction band offset derived from observed quantum number. It was possible to sufficiently use our experimental band parameters for the calculation of the Stark shift in the electric field.     

Influence of Ga(Al)As substrates on surface morphology and critical thickness of InGaAs quantum dots

Influence of Ga(Al)As substrates on surface morphology of InGaAs quantum dots and critical thickness of In_0.5Ga_0.5As film grown by molecular beam epitaxy is investigated. The In_0.5Ga_0.5As quantum dots are grown on (001) surfaces of GaAs and Al_0.25Ga_0.75 A at 450 °C, scanning tunneling microscope images show that the size of quantum dots varied slightly for 10 ML of In_0.5Ga_0.5As grown on GaAs and Al_0.25Ga_0.75As surfaces. Reflection high energy electron diffraction (RHEED) is used to monitor the growth of 4 monolayers (ML) In_0.5Ga_0.5As on Al_0.25Ga_0.75As and GaAs surfaces during deposition. The critical thickness is theoretically calculated by adding energy caused by surface roughness and heat from substrate. The calculations show that the critical thickness of In_0.5Ga_0.5As grown on GaAs and Al_0.25Ga_0.75As are 3.2 ML and 3.8 ML, respectively. The theoretical calculation agrees with the experimental results.