The magnetic-field evolution of Coulomb blockade peaks in lateral InGaAs/InAlAs quantum dots in the few-electron regime is reported. Quantum dots are defined by gates evaporated onto a 60 nm-thick hydrogen silsesquioxane insulating film. A gyromagnetic factor of 4.4 is measured via zero-bias spin spectroscopy and a transition from singlet to triplet spin configuration is found at an in-plane magnetic field B = 0.7 T. This observation opens the way to the manipulation of singlet and triplet states at moderate fields and its relevance for quantum information applications will be discussed.
We present an analysis of gated InGaAs/InAlAs heterostructures, a device platform to realize spinorbitronic functionalities in semiconductors. The phenomenological model deduced from our magnetotransport experiments allows us to correlate the gate response of the studied two-dimensional electron systems to heterostructure design parameters, in particular the indium concentration. We explain the occurrence of metastable electrostatic configurations showing reduced capacitive coupling and provide gate operation strategies to reach classical field effect control in such heterostructures. Our stud…
Elimination of the acoustoelectric domain and increasing of the emission intensity by means of shunting the lateral current in the InGaAs/GaAs heterostructures
We present a study on the influence of strain-relieving InAlAs buffer layers on metamorphic InAs/InGaAs quantum wells grown by molecular beam epitaxy on GaAs. Residual strain in the buffer layer, the InGaAs barrier and the InAs wells were assessed by X-ray diffraction and high-resolution transmission electron microscopy. By carefully choosing the composition profile and thicknesses of the buffer layer, virtually unstrained InGaAs barriers embedding an InAs quantum well with thickness up to 7nm can be grown. This allows reaching low-temperature electron mobilities much higher than previously re…
Anamolous conductance plateau in an asymmetrically biased InAs/InAlAs quantum point contact
在横向自旋-轨道耦合存在下,研究了In0.52Al0.48As/InAs量子点接触(QPC)在0.4(单位为2 e ~ 2/h)处的反常电导平台的出现和演化.异常平台,在通道中的自旋极化的签名,只出现在偏置不对称的中间范围(约3 V)。它是相当稳健的,在两个平面内栅极共用的扫描电压的最大范围内观察到。我们的电导测量结果表明表面粗糙度散射的QPC的侧壁的证据。我们发现,一个强大的垂直磁场导致磁约束在通道中,这降低了从侧壁散射的重要性,有利于近弹道输运通过QPC的发病。
Cyclotron and combined phonon-assisted resonances in double-well heterostructure In$_{0.65}$Ga$_{0.35}$As/In$_{0.52}$Al$_{0.48}$As at megagauss magnetic fields
The InGaAs-InAlAs-InP high electron mobility transistor (InP HEMT) is the preferred active device used in a cryogenic low noise amplifier (LNA) for sensitive detection of microwave signals. We observed that an InP HEMT 0.3-14GHz LNA at 2K, where the in-going transistors were oriented perpendicular to a magnetic field, heavily degraded in gain and average noise temperature already up to 1.5T. Dc measurements for InP HEMTs at 2K revealed a strong reduction in the transistor output current as a function of static magnetic field up to 14T. In contrast, the current reduction was insignificant when …
Monolithic axial InGaAs quantum dot emitters in GaAs-based nanowires via Sb-mediated facet engineering
Walter Schottky Institute, TUM School of Natural Sciences, Technical University of Munich(慕尼黑工业大学沃尔特·施科特基研究所自然科学学院);Institute for Physics and Astronomy, Technical University Berlin(柏林工业大学物理与天文学研究所);Department of Chemistry, Ludwig-Maximilians-University of Munich(慕尼黑大学化学系);Walter Schottky Institute, TUM School of Computation, Information and Technology, Technical University of Munich(慕尼黑工业大学沃尔特·施科特基研究所计算、信息与技术学院);Department of Physics, University of California, Berkeley(加州大学伯克利分校物理系)