We report experimental results of the effect of Ka-band microwave on the spin dynamics of electrons in a 2D electron system in a GaAs/Al0.35Ga0.65As heterostructure, via time-resolved Kerr rotation measurements. While the microwave reduces the transverse spin lifetime of the bulk GaAs when its frequency is close to the Zeeman splitting of the electrons in the magnetic field, it significantly increases that of electrons in the 2D electron system, from 745 ps to 1213 ps. Such a microwave-enhanced spin lifetime is ascribed to the microwave-induced electron scattering which leads to a motional narrowing of spins via DP mechanism.
Convergent beam electron-diffraction investigation of lattice mismatch and static disorder in GaAs/GaAs1-xNx intercalated GaAs/GaAs1-xNx:H heterostructures
The sub-bandgap absorption and ultrafast relaxation in a GaAs/ErAs/GaAs heterostructure are reported. The infrared absorption and 1550 nm-excited ultrafast photo-response are studied by Fourier transform infrared (FTIR) spectrometry and time-domain pump-probe technique. The two absorption peaks located at 2.0 um (0.62 eV) and 2.7 um (0.45 eV) are originated from the ErAs/GaAs interfacial Schottky states and sub-bandgap transition within GaAs, respectively. The photo-induced carrier lifetime, excited using 1550 nm light, is measured to be as low as 190 fs for the GaAs/ErAs/GaAs heterostructure,…
We review magneto-optical and magneto-transport effects in GaAs/GaAlAs heterostructures doped in GaAlAs barriers with donors, providing two-dimensional electron gas in GaAs quantum wells, and additionally doped with smaller amounts of acceptors (mostly Be atoms) in the vicinity of 2DEG. One may also deal with residual acceptors (mostly C atoms). The behavior of such systems in the presence of a magnetic field differs appreciably from those doped in the vicinity of 2DEG with donors.
Heterovalent interlayers and interface states: an ab initio study of GaAs/Si/GaAs (110) and (100) heterostructures
我们从第一性原理出发，研究了GaAs/Si/GaAs（110）和（100）取向突变异质结构中的局域态和共振态的存在，以及充分发展的Si/GaAs（110）异质结中的局域态和共振态。在（100）取向的结构中，我们发现了位于Si/GaAs界面的价带和导带相关的近带边态。相反，在（110）系统中，界面态出现在价带的更深处;最高的价相关共振比GaAs价带最大值低约1 eV。利用它们特有的成键性质和原子特性，我们能够跟踪从充分发展的Si/GaAs二元结到包含2或1 ML Si的三元GaAs/Si/GaAs（110）系统的局域态和共振的演化。这种方法也使我们能够显示（110）和（100）系统的界面状态之间的联系。最后，基于Koster-Slater模型讨论了Si/GaAs（110）界面局域态存在的条件。
Bi-containing III-V semiconductors constitute an exciting class of metastable compounds with wide-ranging potential optoelectronic and electronic applications. However, the growth of III-V-Bi alloys requires group-III-rich growth conditions, which pose severe challenges for planar growth. In this work, we exploit the naturally-Ga-rich environment present inside the metallic droplet of a self-catalyzed GaAs nanowire to synthesize metastable GaAs/GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ axial nanowire heterostructures with high Bi contents. The axial GaAs$_{1-\text{x}}$Bi$_{\text{x}}$ segments are rea…
Magnetization in AIIIBV semiconductor heterostructures with the depletion layer of manganese
本文研究了GaAs/GaPDMATHABMM In $_{0.16}$ As/GaAs异质结构中的磁矩和磁化强度，在温度T=（1.8-300）K和磁场50 kOe范围内，GaAs覆盖层中Mn的浓度是变化的，并且在GaAs量子阱附近的Mn $\sim$层厚度是原子控制的。所有含Mn的GaAs/Ga $_{0.84}$ In $_{0.16}$ As/GaAs样品的质量磁化强度都随着磁场的增加而增加，这表明GaAs基结构的锰耗尽层中存在低维铁磁性。它已被估计的锰含量阈值，在铁磁有序被发现。
Model of circular polarization dependence on Mn delta-layer position in LED heterostructures with InGaAs/GaAs quantum well
提出了具有InGaAs/GaAs量子阱的LED异质结构中Mn δ层位置的圆偏振依赖性的简单模型，能够相当准确地解释最近令人着迷的实验结果[S. V. Zaitsev等人，Physica E（2009），doi：10.1016/j.physe.2008.11.003]。该模型强调了注入的空穴和Mn自旋之间的位置相关的交换相互作用的作用，显着影响的磁场中的空穴能级分裂，导致强烈的变化的极化依赖性。讨论了注入空穴能量对应的有效温度和几何结构缺陷引起的展宽的作用。
Influence of manganese contamination on high-mobility GaAs/AlGaAs heterostructures
光致发光和磁输运测量已被用来评估调制掺杂GaAs/AlGaAs异质结的质量。研究了在分子束外延室中以锰为源材料制备的样品的低温电子迁移率随时间的演化。Mn污染被认为是导致电子迁移率降低到1 x 10^{6} cm^{2}/Vs和出现明显的光致发光带的原因。相比之下，没有这种信号的结构达到5.4 x 10^{6} cm^{2}/Vs的迁移率值。这直接证明了高迁移率电子系统的外延和包含GaMnAs层的结构原则上可以在一个生长室中组合。
We report on the growth of axial InAs-on-GaAs nanowire heterostructures on silicon by molecular beam epitaxy using 20 nm diameter Au catalysts. First, the growth parameters of the GaAs nanowire segment were optimized to achieve a pure wurtzite crystal structure. Then, we developed a two-step growth procedure to enhance the yield of vertical InAs-on-GaAs nanowires. We achieved 90% of straight InAs-on-GaAs nanowires by further optimizing the growth parameters. We investigated the composition change at the interface by energy dispersive X-ray spectroscopy and the nanowire crystal structure by tra…
Modulating the growth conditions: Si as an acceptor in (110) GaAs for high mobility p-type heterostructures
我们实施Si掺杂的（110）GaAs的金属层作为高迁移率p型异质结构中的调制掺杂，改变为单独的掺杂层的p生长条件。强自动补偿掺杂的特点是首先在散装样品，确定的金属-绝缘体的过渡密度和确认经典的跳跃导电绝缘制度。为了克服Si p型（110）生长所固有的不良形态，仅用在p型条件下生长的调制掺杂层来制造异质结构。这种异质结构在密度p=2.4x10^11 cm^-2时，空穴迁移率为1.75x10^2 cm ^2/Vs。我们确定的零场自旋分裂特性的p型异质结，但观察到一个显着的各向同性迁移率和持久的光电导不寻常的p-异质结生长使用其他掺杂技术。这种新的调制生长技术是特别相关的p型劈裂边缘过度生长和III-V族生长室，其中硅是唯一的掺杂剂。
Self-selective growth of GaAs1-xBix on GaAs zinc blende/wurtzite nanowire heterostructures
Lund University（隆德大学）；NanoLund, Lund University（隆德大学纳米隆德）；Centre for Analysis and Synthesis, Lund University（隆德大学分析与合成中心）；MAX IV Laboratory, Lund University（隆德大学MAX IV实验室）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯玻尔研究所）
Interaction correction to conductivity of Al$_x$Ga$_{1-x}$As/GaAs double quantum well heterostructures near the balance
实验研究了Al $_x$ Ga $_{1-x}$ As/GaAs栅双阱结构电导率的电子-电子相互作用量子修正。的电导率张量的温度和磁场依赖性的分析，使我们能够可靠地获得扩散部分的相互作用校正的制度时，结构是平衡的，当只有一个量子阱被占用。令人惊讶的结果是，相互作用校正并没有揭示共振行为;它实际上是相同的两个制度。
Quantum devices formed in high-electron-mobility semiconductor heterostructures provide a route through which quantum mechanical effects can be exploited on length scales accessible to lithography and integrated electronics. The electrostatic definition of quantum dots in semiconductor heterostructure devices intrinsically involves the lithographic fabrication of intricate patterns of metallic electrodes. The formation of metal/semiconductor interfaces, growth processes associated with polycrystalline metallic layers, and differential thermal expansion produce elastic distortion in the active …
The influence of growth interruption on the luminescence properties of the Ga(As,Sb)/GaAs interface have been studied by continous wave and time resolved photoluminescence spectrosocopy in type II Ga(As,Sb)/GaAs/(Ga,In)As double quantum well structures. A specific highly selective etching technique in combination with atomic force microscopy (AFM) is used to analyse the morphology of the Ga(As,Sb) interface layers. The type II charge transfer recombination has been used as sensitive probe. It was found, that highest luminescence quantum efficiency can be achieved using a 10s growth interruptio…
Quantum well (QW) heterostructures have been extensively used for the realization of a wide range of optical and electronic devices. Exploiting their potential for further improvement and development requires a fundamental understanding of their electronic structure. So far, the most commonly used experimental techniques for this purpose have been all-optical spectroscopy methods that, however, are generally averaged in momentum space. Additional information can be gained by angle-resolved photoelectron spectroscopy (ARPES), which measures the electronic structure with momentum resolution. Her…
The electric conductivity behavior in the single and double tunnel-coupled quantum wells (QW) with different doping profile caused by impact of short pulses of the strong longitudinal (in the quantum wells plane) electric field has been investigated. It is established that at low temperatures (4 K) after such impact the long-term metastable state with increased electric conductance may be observed in the case of the asymmetric QW couple with the impurity delta shaped layer in the narrower QW. It is not observed in the structures with other configurations. The observed effect is explained by th…
We probe theoretically the emergence of strong coupling in a system consisting of a topological insulator (TI) and a III-V heterostructure using a numerical approach based on the scattering matrix formalism. Specifically, we investigate the interactions between terahertz excitations in a structure composed of Bi$_{2}$Se$_{3}$ and GaAs materials. We find that the interaction between the Bi$_{2}$Se$_{3}$ layer and AlGaAs/GaAs quantum wells with intersubband transitions (ISBTs) in the terahertz frequency regime creates new hybrid modes, namely Dirac plasmon-phonon-ISBT polaritons. The formation o…
We report on a quasi-nondegenerate pump-probe technique that is based on spectral-filtration of femtosecond laser pulses by a pair of mutually-spectrally-disjunctive interference filters. This cost- and space-efficient approach can be used even in pump-probe microscopy where collinear propagation of pump and probe pulses is dictated by utilization of a microscopic objective. This technique solves the contradictory requirements on an efficient removal of pump photons from the probe beam, to achieve a good signal-to-noise ratio, simultaneously with a needed spectral proximity of the excitation a…
The structure property of non-ideal Si/GaAs heterostructures that were integrated with the ultra-thin oxide (UO) tunneling interfacial layer has been systematically investigated. Si nanomembranes (NMs) were oxidized in different time periods prior to the hetero-integration process to create the non-ideal single-side passivated Si/GaAs heterostructure. The atomic level oxygen distribution and the degree of oxygen content in Si NM and GaAs were carefully investigated using the atom probe tomography (APT) and X-ray photoelectron spectroscopy (XPS) to trace the changes in chemical composition and …
Simultaneous study of acoustic and optic phonon scattering of electrons and holes in undoped $\mathrm{GaAs}$/$\mathrm{Al_{x} Ga_{1-x} As}$ heterostructures
本研究利用非掺杂 GaAs/AlGaAs 异质结构，通过电阻率温度依赖性测量，在 1.6-92.5K 范围内同步研究了二维电子和空穴的声学与光学声子散射，提取了耦合常数和 LO 激活能，验证了该方法的有效性。
Core-shell GaAs-based nanowires monolithically integrated on Si constitute a promising class of nanostructures that could enable light emitters for fast inter- and intrachip optical connections. We introduce and fabricate a novel coaxial GaAs/(In,Ga)As dot-in-a-well nanowire heterostructure to reach spontaneous emission in the Si transparent region, which is crucial for applications in Si photonics. Specifically, we achieve room temperature emission at 1.27 $μ$m in the telecommunication O band. The presence of quantum dots in the heterostructure is evidenced by a structural analysis based on s…
Ab-initio transport theory for digital ferromagnetic heterostructures
由$δ$掺杂GaAs和Mn制成的MnAs/GaAs超晶格被称为数字铁磁异质结构。在这里，我们提出了一个理论密度泛函研究的电子，磁性和输运性质的异质结构。在没有本征施主的情况下，这些系统显示出半金属态密度，交换相互作用比具有相同Mn浓度的随机合金强得多。{ \it Ab initio}弹道输运计算表明，能量接近费米能级的载流子被强烈地限制在MnAs平面周围的几个单层内。这种强约束是大交换耦合的原因。因此，该系统可以被描述为一个二维半金属与大电导的MnAs平面和小电导的垂直方向。
