GaAs/Ge/GaAs Heterostructures for Use in Nonlinear Optics

GaAs/Ge/GaAs heterostructures with sublattice reversed GaAs on Ge epilayers grown via molecular beam epitaxy (MBE) for periodic domain inverted structures are presented. For the first time, such structures are grown in separate MBE machines for GaAs and Ge with atmospheric wafer transfer. The high quality of the heterostructures is confirmed via X-ray diffraction and photoluminescence. It is proposed that the surfactants (Bi, Sb) be used to control the nucleation of GaAs epilayers on a Ge epilayer.     

Electronic structure at the PTCDA/GaAs and NTCDA/GaAs interfaces

The formation of the interface between the GaAs(100) single-crystal surface and PTCDA and NTCDA organic semiconductors is investigated. The method of total current spectroscopy makes it possible to trace the formation of the interfacial electronic structure. The two organic materials and the GaAs substrate are bonded together when the π electron cloud of an aromatic ring spreads toward the substrate. This modifies the electronic states of interfacial organic molecules and generates a dipole at the interface.     

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}     

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：     

Ordering effects in InGaP/GaAs and InGaAsP/GaAs heterostructures grown by LP-MOVPE

Summary The cationic ordering in InGaP epilayers grown by low-pressure vapour phase epitaxy on GaAs substrates has been investigated by X-ray diffraction. The effects of both the substrate miscut and the doping with Si and Zn have been studied. It has been found that ordering effects occur inside relatively small domains on (1–11) and (−111) planes; however, by increasing the miscut angle the domains of the first kind tend to increase their dimensions, while the second ones tend to disappear. Moreover, doping with impurities substituting cations is seen to destroy the order. Photoluminescence anomalies have been revealed and correlated to the size and ordering degree of the ordered domain.     

Photoluminescence characteristics of GaAsSbN/GaAs epilayers lattice-matched to GaAs substrates

The photoluminescence (PL) characteristics of GaAsSbN/GaAs epilayers grown by molecular beam epitaxy (MBE) are carefully investigated. The results show that antimony (Sb) incorporation into GaNAs material has less influence on the N-induced localization states. For the same N concentration, GaAsSbN material can reach an emission wavelength near 1.3 μm more easily than GaInNAs material. The rapid thermal annealing (RTA) experiment shows that the annealing induced rearrangement of atoms and related blueshift in GaAsSbN epilayers are smaller than those in GaNAs and GaInNAs epilayers. The GaAsSbN material can keep a longer emission wavelength near 1.3 μm-emission even after the annealing treatment. Raman spectroscopy analysis gives further insight into the structure stability of GaAsSbN material after annealing.     

GaAs pyramids on GaAs/AlAs Bragg reflectors as alternative microcavities

Pyramidal microcavities are a new class of optical resonators with potentially small mode volume and high quality factor. Our GaAs pyramids with embedded InGaAs quantum dots are placed on top of GaAs/AlAs distributed Bragg reflectors to increase the optical confinement at the base of the pyramids. The pyramidal shape is achieved by a wet-chemical etching process using an AlAs sacrificial layer. Temperature-dependent micro-photoluminescence measurements are used to verify optical modes.     

GaAs/AlAs super-flat interfaces in GaAs/AlAs and GaAs/(GaAs) (AlAs) quantum wells grown on (4 1 1)A GaAs substrates by MBE

Effectively atomically flat GaAs/AlAs interfaces over a macroscopic area (“super-flat interfaces”) have been realized in GaAs/AlAs and GaAs/(GaAs) (AlAs) quantum wells (QWs) grown on (4 1 1)A GaAs substrates by molecular beam epitaxy (MBE). A single and very sharp photoluminescence (PL) peak was observed at 4.2 K from each GaAs/AlAs or GaAs/(GaAs) (AlAs) QW grown on (4 1 1)A GaAs substrate. The full-width at half-maximum (FWHM) of a PL peak for GaAs/AlAs QW with a well width ( ) of 4.2 nm was 4.7 meV and that for GaAs/(GaAs) (AlAs) QW with a smaller well width of 2.8 nm (3.9 nm) was 7.6 meV (4.6 meV), which are as narrow as that for an individual splitted peak for conventional GaAs/AlAs QWs grown on (1 0 0) GaAs substrates with growth interruption. Furthermore, only one sharp peak was observed for each GaAs/(GaAs) (AlAs) QW on the (4 1 1)A GaAs substrate over the whole area of the wafer (7 7 mm ), in contrast with two- or three-splitted peaks reported for each GaAs/AlAs QW grown on the (1 0 0) GaAs substrate with growth interruption. These results indicate that GaAs/AlAs super-flat interfaces have been realized in GaAs/AlAs and GaAs/(GaAs) (AlAs) QWs grown on the (4 1 1)A GaAs substrates.     

利用51微米激光器测量中红外光波导损耗(英文)

一种新型的采用AlGaAs材料设计制成的光波导显示了其在中红外激光器方面的应用。波导部分包含在两个GaAs的包层之间,两个包层的掺杂材料限制光场在波导中传播并且降低损耗。三个不同长度的波导经过切入式测量得到它们的内部传播损耗为1 5dB/cm和耦合损耗为9dB。所采用的中红外激光器的波长是5 1μm,输出功率在45毫瓦以上。从光波导输出的光功率只有几个毫瓦。     

Properties of MnSb/GaAs heterostructures

MnSb layers are deposited on GaAs(100) via the laser ablation of Mn and Sb targets. The magnetic field dependences of the transverse Kerr effect display magnetic anisotropy and magnetization jumps. Measurements of the Hall effect reveal a hysteresis loop at temperatures of up to 300 K.     

A theoretical study on the electronic structure of GaAs/AlAs and AlAs/GaAs core/shell nanoparticles

Results of theoretical investigation on the structural and electronic properties of GaAs/AlAs and AlAs/GaAs core/shell nanoparticles are presented. We have considered relaxed structures of essentially spherical parts of the zinc-blende crystal structure. The electronic properties and the total energy were calculated using density-functional tight-binding method. Our results include the charge distribution, density of states (DOSs), electronic energy levels (in particular HOMO and LUMO), HOMO-LUMO gap, excitation spectra and their variation with shell thickness for both GaAs/AlAs and AlAs/GaAs core/shell systems.     

Impurity cyclotron resonance in InGaAs/GaAs superlattice and InGaAs/AlAs superlattice grown on GaAs substrates

Various temperature measurements of cyclotron resonance (CR) under pulsed ultra-high magnetic field up to 160 T were carried out in InGaAs/GaAs superlattice (SL) and InGaAs/AlAs SL samples grown by molecular beam epitaxy on GaAs substrates. Clear free-electron CR and impurity CR signals were observed in transmission of CO₂ laser with wavelength of 10.6 μm. A binding energy of impurities in these SLs was roughly estimated based on the experiment as result, and we found it was smaller than the previous experimental result of GaAs/AlAs SLs and theoretical calculation with a simple model.     

Growth and characterization of GaAs/InxGa1-xAs/GaAs axial nanowire heterostructures with symmetrical heterointerfaces

We report on the Au-assisted vapour-liquid-solid （VLS） growth of GaAs/InxGal xAs/GaAs （0.2 ≤ x ≤1） axial double-heterostructure nanowires on GaAs （ 111 ） B substrates via the metal-organic chemical vapor deposition （MOCVD） technique. The influence of the indium （In） content in an Au particle on the morphology of nanowires is investigated systematically. A short period of pre-introduced In precursor before the growth of InxGal xAs segment, coupled with a group III precursor interruption, is conducive to obtaining symmetrical heterointerfaces as well as the desired In/Ga ratio in the InxGa1-xAs section. The nanowire morphology, such as kinking and tapering, are thought to be related to the In composition in the catalyst alloy as well as the VLS growth mechanism.     

Orientation-patterned templates GaAs/Ge/GaAs for nonlinear optical devices. I. Molecular beam epitaxy

GaAs/Ge/GaAs heterostructures in which the GaAs layer lattice on Ge is rotated at a right angle to the substrate plane are grown by molecular-beam epitaxy (MBE). Such heterostructures are grown in different epitaxial setups for GaAs and for Ge with wafer transfer through air tor the first time. It is proposed to use surfactants (Bi, Sb) to control GaAs layer nucleation on Ge.     

Orientation-patterned templates GaAs/Ge/GaAs for nonlinear optical devices. II. Investigation of properties

GaAs/Ge/GaAs heterostructures in which GaAs layer lattices are rotated at a right angle in the substrate plane are studied. High quality of heterostructures is confirmed by X-ray diffraction and photoluminescence methods.     

GaAs1-xSbx/GaAs单量子阱的光学特性研究

用选择激发光荧光研究了分子束外延生长的GaAsSb/GaAs单量子阱的光学性质,第一次同时观察到空间直接(Ⅰ类)和间接(Ⅱ类)跃迁.它们表现出不同的特性:Ⅰ类跃迁具有局域化特性,其发光能量不随激发光能量而变;Ⅱ类发光的能量位置随激发功率的增大而蓝移,也随激发光能量的增加而蓝移,复合发光发生在位于异质结GaAs一侧的电子和GaAsSb中的空穴之间,实验结果可以很好地用电荷分离造成的能带弯曲模型来解释,这也是空间间接跃迁的典型特性.还用光荧光的激发强度关系和时间分辨光谱进一步论证了GaAsSb/GaAs能带排列的Ⅱ类特性,并通过简单计算得到了应变和非应变状态下GaAsSb/GaAs异质结的带阶系数.