Robust technology computer-aided design of gated quantum dots at cryogenic temperature

Abstract

We present non-linear Poisson and Schrödinger simulations of an industrially fabricated gated quantum dot device at 100 mK using the Quantum-Technology Computer-Aided Design (QTCAD) software [see https://nanoacademic.com/solutions/qtcad/ “QTCAD: A Computer-Aided Design Tool for Quantum-Technology Hardware, Nanoacademic Technologies Inc.” (2022)]. Using automatic adaptive meshing, the 3D conduction band edge profile of an ultra-thin body and buried oxide fully-depleted silicon-on-insulator field-effect transistor is calculated under steady-state and isothermal conditions. This profile is shown to display potential wells consistent with the experimental observation of side-gate-activated corner quantum dots. The electronic structure of these dots is investigated as a function of applied gate bias within the effective mass theory. Crucially, convergence at 100 mK is shown to be a robust feature of QTCAD's non-linear Poisson solver; convergence is consistently achieved without user intervention for 10 out of 10 random gate bias configurations.