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     

不同散射机理对 Al2O3/InxGa1-xAs nMOSFET 反型沟道电子迁移率的影响

通过考虑体散射、界面电荷的库仑散射以及 Al₂O₃/In_xGa_1-xAs 界面粗糙散射等主要散射机理, 建立了以 Al₂O₃为栅介质In_xGa_1-xAs n 沟金属-氧化物-半导体场效应晶体管 (nMOSFETs) 反型沟道电子迁移率模型, 模拟结果与实验数据有好的符合. 利用该模型分析表明, 在低至中等有效电场下, 电子迁移率主要受界面电荷库仑散射的影响; 而在强场下, 电子迁移率则取决于界面粗糙度散射. 降低界面态密度, 减小 Al₂O₃/In_xGa_1-xAs 界面粗糙度, 适当提高In含量并控制沟道掺杂在合适值是提高 InGaAs nMOSFETs 反型沟道电子迁移率的主要途径. 关键词： InGaAs MOSFET 反型沟道电子迁移率 散射机理     

高迁移率In0.6Ga0.4As沟道MOSHEMT与MOSFET器件特性的研究

从模拟和实验两个方面对高迁移率In_0.6Ga_0.4As沟道金属氧化物半导体高电子迁移率晶体管（MOSHEMT）和金属氧化物半导体场效应晶体管（MOSFET）器件开展研究工作.研宄发现InAlAs势垒层对Ino_0.6Ga_0.4AsMOSHEMT的特性具有重要影响.与Ino_0.6Ga_0.4As MOSFET相比,Ino_0.6Ga_0.4As MOSHEMT表现出优异的电学特性.实验结果表明,In_0.6Ga_0.4As MOSHEMT的有效沟道迁移率达到2812 cm²/V.s^-1,是In_0.6Ga_0.4As MOSFET的3.2倍.0.02 mm栅长的MOSHEMT器件较相同栅长的MOSFET器件具有更高的驱动电流、更大的跨导峰值、更大的开关比、更高的击穿电压和更小的亚阈值摆幅.     

高In组分InxGa1－xN/GaN多量子阱材料电致荧光谱的研究

研究了高In组分In_xGa_1-xN/GaN（x≈30%）多量子阱（MQWs）结构 发光二极管样品在不同注入电流下的电致荧光（EL）谱及反常的双峰现象.结果表明：有源区 内建电场在外界电流注入条件下逐渐受屏蔽，这一效应在高In组分In_xGa_{1 -x}N/GaN MQWs材料的发光复合机理中占有重要地位. 关键词： xGa_1-xN/GaN多量子阱')" href="#">In_xGa_1-xN/GaN多量子阱 电致荧光谱 内建电场     

超晶格中GaAs/InGaAs界面与InGaAs/GaAs界面的特性差异

In_xGa_1-xAs缓冲层上生长In_yGa_1-yAs/GaAs超晶格（x＜y）．阱层处于压缩应变，垒层处于伸张应变，其厚度均小于Mathews-Blakeslee（M-B）平衡理论计算的临界厚度．透射电子显微镜及俄歇电子能谱、二级离子质谱测试发现，GaAs/In_yGa_1-yAs界面铟组分过渡区比In_yGa_1-yAs/GaAs界面铟组 关键词：     

赝形InxGa1-xAs/In0.52Al0.48As异质结构中二维电子气的回旋共振光谱研究

采用回旋共振光谱方法，同时获得了具有较高电子气浓度的赝形In_0.80Ga_0.20As/In_0.53Ga_0.47As/In_0.52Al_0.48AsHEMT结构中最低两个子能带的费密面附近电子有效质量、 散射时间和迁移率.观察到该系统中能带非抛物性和波函数穿透所导致的电子回旋有效质量的显著增大效应，以及合金无序势和电离杂质散射所引起的电子散射时间和迁移率明显的子带依赖性. 关键词：     

空间用GaInP/GaAs/In0.3Ga0.7 As(1 eV)倒装三结太阳电池研制

采用阶变缓冲层技术 (step-graded) 外延生长了具有更优带隙组合的倒装GaInP/GaAs/In_0.3Ga_0.7As(1.0 eV) 三结太阳电池材料, TEM和HRXRD测试表明晶格失配度为2%的In_0.3Ga_0.7As 底电池具有较低的穿透位错密度和较高的晶体质量, 达到太阳电池的制备要求. 通过键合、剥离等工艺制备了太阳电池芯片. 面积为 10.922 cm² 的太阳电池芯片在空间光谱条件下转换效率达到32.64% (AM0, 25 ℃), 比传统晶格匹配的 GaInP/GaAs/Ge(0.67 eV) 三结太阳电池的转换效率提高3个百分点. 关键词： 太阳电池 三结 倒装结构     

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     

InAs/GaAs和InAs/InxGa1-xAs/GaAs纳米线异质结构的生长研究

利用金辅助金属有机化学气相沉淀法(MOCVD)在GaAs(111)B衬底上分别制备了InAs/GaAs和InAs/In _{x Ga1-xAs/GaAs(0≤x≤1)纳米线异质结构.实验结果显示,直接生长在GaAs纳米线上的InAs纳米线生长方向杂乱或者沿着GaAs纳米线侧壁向衬底方向生长,生长的含有In x Ga1-xAs组分渐变缓冲段的InAs/In x Ga1-x关键词： 纳米线异质结构 xGa1-xAs')" href="#">InxGa1-xAs 组分渐变缓冲层 金属有机化学气相沉淀法}     

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：     

利用In0.82Ga0.18As与InP衬底之间的应力制作结构材料的缓冲层

采用低压金属有机化学气相淀积(LP-MOCVD)技术,在InP(100)衬底上生长In0.82Ga0.18As,研究生长温度对In0.82Ga0.18As材料表面形貌、结晶质量和电学性能的影响.利用InP(100)衬底与In0.82Ga0.18As材料晶格失配所产生的应变,在不同的生长温度下应变释放程度不同,进而在In...     

Growth condition optimization and mobility enhancement through inserting AlAs monolayer in the InP-based In_xGa_(1-x)As/In_(0.52)Al_(0.48)As HEMT structures

The structure of In P-based In_xGa_(1-x) As/In0.52Al0.48 As pseudomorphic high electron mobility transistor(PHEMT)was optimized in detail.Effects of growth temperature,growth interruption time,Si δ-doping condition,channel thickness and In content,and inserted Al As monolayer(ML) on the two-dimensional electron gas(2DEG) performance were investigated carefully.It was found that the use of the inserted Al As monolayer has an enhancement effect on the mobility due to the reduction of interface roughness and the suppression of Si movement.With optimization of the growth parameters,the structures composed of a 10 nm thick In0.75Ga0.25 As channel layer and a 3 nm thick Al As/In0.52Al0.48 As superlattices spacer layer exhibited electron mobilities as high as 12500 cm~2·V-1·s~(-1)(300 K) and 53500 cm~2·V~(-1_·s~(-1)(77 K) and the corresponding sheet carrier concentrations(Ns) of 2.8×10~(12)cm~(-2)and 2.9×1012cm~(-2),respectively.To the best of the authors' knowledge,this is the highest reported room temperature mobility for In P-based HEMTs with a spacer of 3 nm to date.     

GaN/In_xGa_(1-x)N型最后一个量子势垒对发光二极管内量子效率的影响

GaN/In_xGa_(1-x)N型最后一个量子势垒结构能有效提高发光二极管(LED)器件内量子效率,缓解LED效率随输入电流增大而衰减的问题.本文综述了该结构及其结构变化——In组分梯度递增以及渐变、GaN/In_xGa_(1-x)N界面极化率改变等对改善LED器件性能的影响及优势,归纳总结了不同结构的GaN/In_xGa_(1-x)N型最后一个量子垒的工作机理,阐明极化反转是该结构提高LED性能的根本原因.在综述该结构发展的基础之上,通过APSYS仿真计算,进一步探索和深入分析了该结构中In_xGa_(1-x)N层的In组分及其厚度变化对LED内量子效率的影响.结果表明:In组分的增加有助于在GaN/In_xGa_(1-x)N界面产生更多的极化负电荷,增加GaN以及电子阻挡层处导带势垒高度,减少电子泄漏,从而提高LED的内量子效率;但GaN/In_xGa_(1-x)N型最后一个量子势垒中In_xGa_(1-x)N及GaN层厚度的变化由于会同时引起势垒高度和隧穿效应的改变,因而In_xGa_(1-x)N和GaN层的厚度存在一个最佳比值以实现最大化的减小漏电子,提高内量子效率.     

Control of symmetric properties of metamorphic In_(0.27)Ga_(0.73)As layers by substrate misorientation

Asymmetry in dislocation density and strain relaxation has a significant impact on device performance since it leads to anisotropic electron transport in metamorphic materials. So it is preferred to obtain metamorphic materials with symmetric properties. In this paper, we grew metamorphic In_(0.27)Ga_(0.73) As epilayers with symmetric low threading dislocation density and symmetric strain relaxation in two (110) directions using In Al Ga As buffer layers on 7°misoriented Ga As(001)substrates. To understand the control mechanism of symmetric properties of In_(0.27)Ga_(0.73) As layers by the substrate miscut angles, In_(0.27)Ga_(0.73) As grown on 2°and 15°misoriented substrates were also characterized as reference by atomic force microscopy, transmission electron microscopy, and high resolution triple axis x-ray diffraction. The phase separation and interaction of 60°misfit dislocations were found to be the reasons for asymmetry properties of In_(0.27)Ga_90.73 As grown on 2and 15°substrates, respectively. Photoluminescence results proved that the In_(0.27)Ga_(0.73) As with symmetric properties has better optical properties than the In_(0.27)Ga_(0.73) As with asymmetric properties at room temperature. These results imply that high quality metamorphic In_(0.27)Ga_(0.73) As can be achieved with controllable isotropic electron transport property.     

Influence of thermal annealing duration of buffer layer on the crystalline quality of In0.82Ga0.18As grown on InP substrate by LP-MOCVD

In_0.82Ga_0.18As epilayers were grown on InP substrates using a two-step growth technique by LP-MOCVD. A homogeneous low-temperature (450 °C) In_0.82Ga_0.18As buffer layer was introduced to improve the crystalline quality of epilayers. The influence of low-temperature buffer layer deposition condition, such as thermal annealing duration, on the crystalline quality of the In_0.82Ga_0.18As epilayer was investigated. Double-crystal X-ray diffraction measurement, Hall measurement, and Raman scattering spectrum were used to evaluate the In_0.82Ga_0.18As epilayers. Atomic force microscope was used to study the surface morphology. It is found that the In_0.82Ga_0.18As epilayer, with buffer layer thermal annealing for 5 min, exhibits the best crystalline quality. The change of the surface morphology of the buffer layer after thermal annealing treatment was suggested to explain the phenomenon.     

Surface deformation phenomena induced by electron-beam irradiation in strained InGaAs/AlGaAs layers on GaAs (1 0 0) and (3 1 1)B substrates

The strained InGaAs/AlGaAs layer structures have been grown on GaAs ( 10 0) and (3 1 1)B substrates in a horizontal low-pressure metalorganic vapor-phase epitaxy system at a temperature of 800°C. In the surface observation using a high-resolution scanning electron microscope, we have found that surface deformation phenomena induced by electron-beam irradiation in strained In_0.36Ga_0.64As,/Al_0.3Ga_0.7As layers on GaAs (1 0 0) and (3 1 1)B substrates. The change of the surface morphology was observed in real time on the display of SEM with the accelerating voltage of 30 kV and the irradiated time of 60–120 s. The surface deformation through mass transport seems to be the cause of the residual strain relaxation due to electron-beam irradiation.     

Improved thermal property of strained InGaAlAs/AlGaAs quantum wells for 808-nm vertical cavity surface emitting lasers

The 808-nm vertical cavity surface emitting laser (VCSEL) with strained In_0.13Ga_0.75Al_0.12As/Al_0.3Ga_0.7As quantum wells is designed and fabricated. Compared with the VCSELs with Al_0.05Ga_0.95As/Al_0.3Ga_0.7As quantum wells, the VCSEL with strained In_0.13Ga_0.75Al_0.12As/Al_0.3Ga_0.7As quantum wells is demonstrated to possess higher power conversion efficiency (PCE) and better temperature stability. The maximum PCE of 43.8% for 10-μm VCSEL is achieved at an ambient temperature of 30 ℃. The size-dependent thermal characteristics are also analyzed by characterizing the spectral power and output power. It demonstrates that small oxide-aperture VCSELs are advantageous for temperature-stable performance.     

High performance uncooled InAsSbP/InGaAs photodiodes for the 1.8–3.4 μm wavelength range

Room temperature In_0.97Ga_0.03As photodiodes with an InAs_0.36Sb_0.20P_0.44 transparent window layer operating in the mid-infrared region over the wavelength range 1.8–3.4 μm are reported. The InAs_0.36Sb_0.20P_0.44/In_0.97Ga_0.03As heterojunction photodiodes were grown on p-type (100) InAs substrates by liquid phase epitaxy (LPE). Basic detector characteristics have been measured and compared with other detectors in this wavelength range. The typical detectivity of the photodiodes is 1.2 × 10¹⁰ cm Hz^1/2/W at room temperature, which compares very favourably with that of TE cooled HgCdTe and is at least three times that of cooled PbSe photoconductors. The InAs_0.36Sb_0.20P_0.44/In_0.97Ga_0.03As heterojunction photodiodes offer the advantage of increased sensitivity and extended wavelength response at room temperature compared with that of currently available commercial photodetectors, making them an attractive alternative for a number of mid-infrared applications including optical gas sensors and infrared spectrometers.