Impact of Layer Structure and Strain on Morphology and Electronic Properties of InAs Quantum Wells on InP (001)

Abstract

High-quality InAs quantum wells grown on InP are a promising platform for topological quantum information processing due to their large g-factor, strong Rashba spin-orbit interaction, and their compatibility with in-situ-deposited superconductors. In this work, we investigate InAs/InGaAs quantum wells grown on InP (001) wafers, focusing on how the layer structure and strain influence the electronic properties and surface morphology. By combining quantum transport measurements with atomic force microscopy, we show that the layer design predominantly affects the mobility anisotropy, which aligns well with the surface morphology. Surface characterization further reveals the mechanism of quantum well collapse when the layer thickness exceeds the strain limit. In addition, transport measurements demonstrate that quantum confinement has a clear impact on band nonparabolicity.

Figures (6)

• Figure 1: (a) Schematic image of InAs QW layer-structure. (b) Electron mobility vs density of Sample A, B and C along $[110]$ and $[1\overline{1}0]$ directions, measured from "L"-shape Hall bars with global top gates at 1.7 K. Inset: Same Hall bar based on Sample B, but measured at 10 mK, showing the peak mobility reaching $1.03\times 10^6 \:\rm{cm^2/Vs}$.
• Figure 2: (a), (b) and (c) Successive AFM surface characterization of Sample B, D and E. The measurement range is $10\:\rm{\mu m}\times 10\: \rm{\mu m}$. Crystal directions $[110]$ and $[1\overline{1}0]$ are labeled. (d) and (e) are line cut (white arrows) of Sample B and D along $[110]$ and $[1\overline{1}0]$. The appearing deep grows along $[110]$ are labeled with black arrows in both (b) and (e).
• Figure 3: (a) Temperature dependence of the SdH oscillations measured on Sample B, where $n = 2.33 \times 10^{11} \rm{cm^{-2}}$. (b) Fitting of the Dingle factor based on the local maxima and minima in (a). (c) Fitted effective mass $m^*$ vs $B$. In a wide range of $B$, $m^*$ shows an average value of $(2.28\pm0.02)\times 10^{-2} m_0$ (dashed line), and the error is indicated with shadow.
• Figure 4: (a) $\rho_{xx}$ vs $B$ on both $[110]$ and$[1\overline{1}0]$ directions. Beating of the SdH oscillations are observed in both traces. inset: the fast Fourier transform of the SdH oscillation, measured along two directions. (b) The oscillation part of the longitudinal resistivity, $\Delta\rho_{xx}$ as the function of $1/B$. Both directions are presented.
• Figure 5: (a), (b) and (c) Successive AFM surface characterization of Sample B, D and E in a large scale ($\rm{30\mu m \times 30\mu m}$). Figures presented in the main contents are zoom-in measurement of the area indicated with white boxes. Crystal directions $[110]$ and $[1\overline{1}0]$ are labeled.