Donor implanted Back-gates in GaAs for MBE-grown highest mobility two-dimensional electron systems

TL;DR

This study investigates ion-implantation of Silicon, Selenium, and Tellurium into GaAs to create back-gates for high-mobility 2DEGs, finding Silicon and Selenium effective while Tellurium damages the material.

Contribution

It demonstrates that Silicon and Selenium ion-implantation can produce functional back-gates in GaAs for high-quality 2DEGs, with Silicon allowing electron density tuning.

Findings

Silicon and Selenium achieve similar 2DEG mobility to non-implanted samples.

Tellurium causes excessive damage, hindering back-gate formation.

Silicon back-gates can be tuned via electron density adjustments.

Abstract

Three different elements, Silicon, Selenium, and Tellurium, are ion-implanted in Gallium arsenide to form a conducting layer that serves as a back-gate to a molecular beam epitaxy (MBE) overgrown two-dimensional electron gas (2DEG). While the heavy ion Tellurium creates too many damages in the gallium arsenide to form a conducting layer, both Silicon and Selenium show promising results combined with MBE-grown high-quality 2DEGs. Similar 2DEG mobility compared to non-implanted reference samples is achieved for both Silicon and Selenium implanted structures. Individual contacts to the back-gate are challenging. However, Silicon implanted structures, annealed before the MBE growth, result in a function back-gate, and the electron density of the 2DEG is tuned via the back-gate.