Growth, characterization, and transport calculation of Ge/SiGe heterojunction: strategy for the growth of undoped Ge quantum wells

Abstract Ge/SiGe heterostructure quantum wells play a pivotal role in the pursuit of scalable silicon-based qubits. The varying compressive strains within these quantum wells profoundly influence the physical characteristics of the qubits, yet this factor remains largely unexplored, driving our research endeavor. In this study, we utilized RP-CVD (Reduced Pressure Chemical Vapor Deposition) to grow Ge quantum wells with varied compressive strain, proposing growth schemes for lightly-strained ( ε ∥ = −0.43%) QW (quantum well), standard-strained ( ε ∥ = −0.61%) QW, and heavily-strained ( ε ∥ = −1.19%) QW. Through comprehensive material characterization, particularly employing the low-temperature magneto-transport measurements, we derived the percolation densities ranging from 4.7 × 10 10 to 14.2 × 10 10 cm −2 and mobilities from 3.382 × 10 5 to 7.301 × 10 5 cm 2 ∙V −1 ∙s −1 . Combined with the first-principles calculations, our analysis delves into the trends in effective mass and percolation density at low temperatures, shedding light on the impact of quantum effects on band structures and the interplay between structural components and wave functions. This research offers a comprehensive investigation into the intrinsic mechanisms governing complex multi-strained quantum wells, spanning growth, characterization, and computational perspectives, thereby establishing a strategy for the growth of high-quality strained quantum wells.