选择液相外延法制备GaAs SNOM微探尖

使用GaAs(001)衬底模拟垂直腔面发射激光器(VCSEL)外延片表面,采用选择液相外延技术在其上面制备了用于超高密度光存储的扫描近场光学显微术GaAs微探尖阵列,并用扫描电子显微镜对微探尖阵列进行了表征.结果表明,在合适的条件下,微探尖呈金字塔状,并且有着较好的分布周期性.这对解决微探尖与VCSEL出光窗口的对准问题、批量制备问题和实现多探尖并行扫描具有实际应用价值.     

选择液相外延法制备GaAs SNOM微探尖

使用GaAs（001）衬底模拟垂直腔面发射激光器（VCSEL）外延片表面，采用选择液相外延技术在其上面制备了用于超高密度光存储的扫描近场光学显微术GaAs微探尖阵列，并用扫描电子显微镜对微探尖阵列进行了表征．结果表明，在合适的条件下，微探尖呈金字塔状，并且有着较好的分布周期性．这对解决微探尖与VCSEL出光窗口的对准问题、批量制备问题和实现多探尖并行扫描具有实际应用价值．     

LPE-GaAs微探尖与VCSEL的粘合集成

介绍了应用于扫描近场光学显微术(SNOM)传感头的GaAs微探尖与垂直腔表面发射激光器(VCSEL)的粘合集成方法,并利用扫描电子显微镜对集成后的微探尖与VCSEL进行了表征.结果表明,该种方法能够成功地将微探尖转移并集成到VCSEL的出光窗口上,实现微探尖与出光窗口的对准,并且整个过程中不会对微探尖造成损伤.这种技术对进一步实现由带有PIN光探测器的VCSEL与GaAs微探尖的混合集成式SNOM传感头有着重要的应用价值.     

基于金属背支撑刻蚀技术的柔性AlGaInP/AlGaAs/GaAs三结太阳电池研制

对柔性GaAs基太阳电池的制备方法进行研究,报道了一种用于制备柔性倒置生长的AlGaInP/AlGaAs/GaAs三结太阳电池的剥离和转移方法——金属背支撑选择性湿法刻蚀技术.在GaAs/GaInP选择性腐蚀的基础上进行了GaAs衬底层的腐蚀,研究了不同类型和体积比的溶液对GaAs/GaInP/AlInP结构腐蚀的选择特性,最终选用不同配比的H2 SO4-H2 O2系腐蚀液,获得快速、可控制、重复性好的去除衬底的两步腐蚀法.原子力显微镜测试结果表明,通过此方法能够成功地将电池外延层薄膜转移到Cu衬底上,并且在剥离和转移过程中外延层薄膜没有受到损伤.柔性AlGaInP/AlGaAs/GaAs三结太阳电池的开路电压超过3.4V.     

GaAs/AlGaAs核-壳结构纳米线的生长研究

GaAs/AlGaAs核-壳结构纳米线是制作金属-半导体-金属(MSM)型高速光电探测器最简洁有效的光电材料之一。采用金属有机化学气相沉积(MOCVD)设备,在GaAs(111)B衬底上开展了GaAs/AlGaAs核-壳结构纳米线的生长研究,用场发射扫描电子显微镜(SEM)和微区光荧光谱仪(PL)对制备的GaAs/AlGaAs核-壳结构纳米线样品进行了测试分析。采用已优化的GaAs/AlGaAs核-壳结构纳米线的生长工艺参数,主要研究了AlGaAs壳材料的生长机制,获得了高质量的AlGaAs壳材料,AlGaAs壳材料生长速率约为50 nm/min,Al的原子数分数为14%。这些结果为将来多异质结构纳米线的生长和光电探测器的制备奠定了基础。     

InGaAs／AlGaAs单量子阱激光器低阈值激射

研制了InGaAs/AlGaAs SQW激光器,对其工作特性如阈值电流密度、激射波长、特征温度、远场分布等进行了研究. 用MOCVD方法生长制备了InGaAs/AlGaAs分别限制单量子阱结构材料,得出其各层组分和能带分布.首先在GaAs衬底上生长GaAs缓冲层和AlGaAs波导层,然后生长窄能带的AlGaAs量子阱势垒层,再继续生长InGaAs量子阱有源区.其后继续生长AlGaAs势垒层、高Al组分AlGaAs波导层和GaAs高掺杂欧姆接触层.我们发现在低温范围里(160 K～220 K)阈值电流密度随温度升高而减小,与普通量子阱激光器正相反,表现出负的特征温度.随着温度进一步提高,阈值电流密度表现出指数式增大.300 K下腔长2000 μm的激光器最低的阈值电流密度约为200 A/cm2.(OD7)     

基于HgCdTe薄膜和GaAs／AlGaAs多量子阱的红外光电探测器列阵

俄罗斯科学院西伯利亚分院半导体物理研究所设计并制作了若干用于3μm～12μm光谱范围的光电探测器组件.这些光电探测器组件都是以用分子束外延方法生长的Hg1-xCdxTe/GaAs异质结构和GaAs/AlGaAs多量子阱结构为基础的,其HgCdTe光敏层长在带CdZnTe中间缓冲层的GaAs衬底上.为了减少表面对复合过程的影响,生长了增加表面组分的渐变带隙HgCdTe层.     

微机械可调谐滤波器的研制

利用GaAs/AlGaAs分布反馈Bragg反射镜在GaAs衬底上制作了一个微机械的调谐滤波器.该器件在7V调谐电压下调谐范围达28nm.     

RHEED振荡精确测量AlGaAs生长速率研究

采用分子束外延技术,在GaAs衬底上生长GaAs,AlAs和AlGaAs时,实现RHEED图像和RHEED强度振荡的实时监测已被证明是一种有效工具。通过RHEED可讨论GaAs表面结构和生长机制,并可以估算衬底温度,更重要的是能计算出材料的生长速率。RHEED强度振荡周期决定生长速率,每一个周期对应一个单层。实验测量GaAs的生长周期为0.82s,每秒沉积1.22单分子层,AlAs的生长周期为2.35s,每秒沉积0.43单分子层。     

生长温度对于Ge衬底上分子束外延生长的InGaAs/GaAs量子阱结构质量的影响

本文研究了斜切割（100）Ge衬底上InxGa1-xAs/GaAs量子阱结构的分子束外延生长（In组分为0.17或者0.3）。所生长的样品用原子力显微镜、光致发光光谱和高分辨率透射电子显微镜进行了测量和表征。结果发现,为了生长没有反相畴的GaAs缓冲层,必须对Ge衬底进行高温退火。在GaAs外延层和InxGa1-xAs/GaAs量子阱结构的生长过程中,生长温度是一个至关重要的参数。文中讨论了温度对于外延材料质量的影响机理。通过优化生长温度,Ge衬底上的InxGa1-xAs/GaAs量子阱结构的光致发光谱具有很高的强度、很窄的线宽,样品的表面光滑平整。这些研究表面Ge 衬底上的III-V族化合物半导体材料有很大的器件应用前景。     

Transferring of GaAs microtips using selective wet etching Al0.7Ga0.3As sacrificial layer

GaAs pyramidal microtips were successfully transferred from GaAs substrate to target wafer by a simple technique, i.e., selective wet etching off AlGaAs sacrificial layer. A GaAs/Al_0.7Ga_0.3As/GaAs sandwich structure is firstly formed on GaAs (0 0 1) substrate by metalorganic chemical vapor deposition, and then GaAs pyramidal microtips are grown on the sandwich structure using selective liquid-phase epitaxy. The GaAs microtips are removed from the sandwich structure by selective wet etching Al_0.7Ga_0.3As layer using concentrated HCl solution. Finally, the tips are glued onto the target wafer by a negative photoresist. During this transfer process the tips are completely encapsulated in a positive photoresist to protect against attack. Scanning electron microscopy images show that GaAs tips can be successfully transferred without any damage by this technique. The achievement reported here represents a significant step towards the application of scanning near-field optical microscopy.     

Reduction of backgating effect in MBE-Grown GaAs/AlGaAs HEMT's

We have investigated the backgating effect in high electron mobility transistors (HEMT's) fabricated on MBE-grown GaAs/AlGaAs layers, which is undesirable for LSI fabrication. Comparing five different types of devices, we related the backgating effect to the interface between the GaAs substrate and the undoped GaAs buffer layer. By using a thermally etched GaAs substrate, we successfully reduced the backgating to the same order as that of ion-implanted GaAs MESFET's.     

Theoretical study of the effect of an AlGaAs double heterostructureon metal-semiconductor-metal photodetector performance

The impulse and square-wave input response of different GaAs metal-semiconductor-metal photodetector (MSM) designs are theoretically examined using a two dimensional drift-diffusion numerical calculation with a thermionic-field emission boundary condition model for the heterojunctions. The rise time and the fall time of the output signal current are calculated for a simple GaAs, epitaxially grown, MSM device as well as for various double-heterostructure barrier devices. The double heterostructure devices consist of an AlGaAs layer sandwiched between the top GaAs active absorption layer and the bottom GaAs substrate. The effect of the depth of the AlGaAs layer on the speed and responsivity of the MSM devices is examined. It is found that there is an optimal depth, at fixed applied bias, of the AlGaAs layer within the structure that provides maximum responsivity at minimal compromise in speed     

Pair-groove-substrate GaAs/AlGaAs multiquantum-well lasers with a self-aligned stripe geometry

GaAs/AlGaAs multiquantum-well (MQW) lasers with a self-aligned structure incorporating a waveguide and current confinement were fabricated on a substrate with a pair of etched grooves using two-step epitaxial growth. First, a current-blocking layer was grown selectively on the substrate by low-pressure organometallic vapour-phase epitaxy (OMVPE), and then the GaAs/AlGaAs MQW laser structure was constructed on the substrate with the OMVPE layer by molecular-beam epitaxy. The mesa-shaped part of the active layer above the current-confinement region provides a lateral refractive-index optical waveguide. The lasers show well controlled transverse-mode oscillations with low threshold currents.     

Monolithic integration of an AlGaAs/GaAs DH LED with a GaAs FET driver

An AlGaAs/GaAs double heterostructure light emitting diode (LED) and a GaAs field effect transistor (FET) have been monolithically integrated on a GaAs substrate using a combination of liquid phase and molecular beam epitaxies. The electrical isolation between LED and FET has been achieved by inserting a molecular beam-grown high resistivity AlGaAs layer. A linear gate voltage-to-light power transfer characteristic with a 13 ns time constant has been demonstrated.     

Study of internal electric fields in AlGaAs/GaAs two-dimensional electron gas heterostructures

Modulation-doped GaAs/AlGaAs heterostructures have been studied by photoreflectance spectroscopy. The spectra at room temperature show Franz–Keldysh oscillations associated to the substrate–buffer layer interface. The built-in electric field magnitude calculated from these oscillations is related with the two-dimensional electron gas (2DEG) mobility. In addition we observed two signals associated to the GaAs capping layer and to the 2DEG, respectively.     

Etching behavior of GaAs/AlGaAs multilayer structure during laser beam scanning

The thermochemical etching behavior of GaAs/AlGaAs multilayer structure during laser beam scanning has been studied. The etch rate changes between GaAs and AlGaAs epilayers as the etching process proceeds through the layered sample. The phenomenon can be explained by the difference of thermal parameters of the heterojunction interface. The local temperature rise from laser irradiation has been calculated to investigate etching characteristics for GaAs and AlGaAs. It is concluded that the good thermal confinement at GaAs/AlGaAs interface produces the wider etch width of GaAs layer than that of AlGaAs layer in GaAs/AlGaAs multilayer. The maximum etch rate of the GaAs/AlGaAs multilayer was 32.5 μm/sec and the maximum etched width ratio of GaAs to AlGaAs was 1.7.