Study of Charge Distributions and Electrical Properties in GaAs/AlGaAs Single Quantum Well/Nanowire Heterostructures

Abstract

By embedding quantum wells (QWs) in semiconductor nanowires (NWs), the confined electronic states perpendicular to the NW axis as well as free movements along the NW axis can be simultaneously achieved. Among them, AlGaAs NWs are ideal candidates for radial two-dimensional GaAs QWs because of their nearly perfect lattice matching, negligible piezoelectric, and strain effects. A series of studies based on AlGaAs NWs with embedded QWs have revealed novel electronic states and outstanding properties. On the other hand, their electrical properties and underlying mechanism at the nanometer scale have less been reported. Herein, the electrical properties of GaAs QW/AlGaAs NW interfaces are quantitatively characterized via off-axis electron holography. Our results reveal that considerable electrons are confined in the GaAs QW, leaving massive holes distributing at the GaAs/AlGaAs hetero-interfaces. In addition, in combination with the first-principles calculations, the redistribution of charges causing band bending at GaAs/AlGaAs interfaces is calculated, which complies well with our experiment. The quantum confinement effect in this heterostructure due to the introduction of GaAs QW is also revealed, which causes the change of related band gap, leading to blue-shift in photoluminescence (PL) spectra. This work provides insight into the nanometer-scale electrical properties of III–V semiconductor NWs comprising QW, which may shed light on optimizing similar hybrid structures as optoelectronic devices in the future.

Cathodoluminescence visualisation of local thickness variations of GaAs/AlGaAs quantum-well tubes on nanowires

“…Their shape means that these radial QWs are referred to as quantum-well tubes (QWTs) [9]. Due to the ability of the NWs to accommodate strain, it is possible to grow defect free heterostructures that are difficult to achieve with planar growth and QWTs have been grown in several III-V and III-Nitride semiconductor material systems, namely InGaAs/InP [3], InGaAs/GaAs [10], GaAs/AlGaAs [9,[11][12][13], GaAs/GaAsP [14], GaInP/GaP [15] and InGaN/GaN [16]. NWs with QWTs have some specific applications, in particular as lasers where the high gain of the QWs can reduce the threshold [5,[17][18][19][20][21].…”

Schottky barrier inhomogeneities at the interface of different epitaxial layer thicknesses of n-GaAs/Ti/Au/Si: Al0.33Ga0.67As

“…The growth temperature is 610 C; the growth rates are 1 μm per hour for GaAs and 0.5 μm for AlAs, and arsenic overpressure is 1.2 Â 10 À5 Torr. The epitaxial layer structures consisted of 1 μm GaAs (n ¼ 3Â10 16 ) buffer layer followed by 1.5 μm for sample N1, and 2 μm for sample N2 Si-doped Al 0.33 Ga 0.67 As layer. Schottky contacts were prepared by evaporating Ti/Au metal on the top layer and developed ohmic contacts based on the n þ -GaAs substrate to evaporate Ge/Au/Ni/Au.…”

“…It is assumed that Li et al [ 16 ] have only investigated the electrical properties of GaAs/AlGaAs heterostructures in 2019, which can provide useful information about the improvement in these structures, even though these diodes have been examined for more than four decades. Therefore, this study has reported the impact of epitaxial layer thickness on the Schottky barrier height (SBH) and the ideality factor in Al 0.33 Ga 0.67 as elevated by molecular beam epitaxy (MBE) throughout the temperature range of 300–420 K.…”

SHORYUKEN: An Open-Source Software Package for Calculating Nonlocal Exchange Interactions in Nanowires

“…In particular, semiconducting nanowires have already shown immense potential in high-power devices and electronics due to their tailorable bandgaps and enhanced electron mobilities [1,2,3]. Specifically, the emergence of a two-dimensional electron gas (2DEG) at the heterojunction interface in core-shell nanowires [4,5] can be further manipulated to enable unique quantum properties in these nanostructures. By modulating the doping density and geometry of the nanowire, a sheet of high-density electrons or a quasi-one-dimensional electron gas (Q1DEG) can form at the interface [6,7].…”