Kavli Affiliate: Giordano Scappucci
| First 5 Authors: Davide Costa, Lucas E. A. Stehouwer, Yi Huang, Sara MartÃ-Sánchez, Davide Degli Esposti
| Summary:
We investigate the disorder properties of two-dimensional hole gases in
Ge/SiGe heterostructures grown on Ge wafers, using thick SiGe barriers to
mitigate the influence of the semiconductor-dielectric interface. Across
several heterostructure field effect transistors we measure an average maximum
mobility of $(4.4 pm 0.2) times 10^{6}~mathrm{cm^2/Vs}$ at a saturation
density of $(1.72 pm 0.03) times 10^{11}~mathrm{cm^{-2}}$, corresponding to
a long mean free path of $(30 pm 1)~mathrm{mu m}$. The highest measured
mobility is $4.68 times 10^{6}~mathrm{cm^2/Vs}$. We identify uniform
background impurities and interface roughness as the dominant scattering
mechanisms limiting mobility in a representative device, and we evaluate a
percolation-induced critical density of $(4.5 pm 0.1)times 10^{9}
~mathrm{cm^{-2}}$. This low-disorder heterostructure, according to
simulations, may support the electrostatic confinement of holes in gate-defined
quantum dots.
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