Modulating the growth conditions: Si as an acceptor in (110) GaAs for high mobility p-type heterostructures

TL;DR

This paper demonstrates a novel Si doping method in (110) GaAs heterostructures that achieves high mobility p-type layers with unique properties, improving understanding and potential applications of Si as an acceptor.

Contribution

It introduces a new modulation doping technique using Si in (110) GaAs, enabling high mobility p-type heterostructures with distinctive electronic and optical characteristics.

Findings

Achieved hole mobility of 175 cm^2/Vs at p=2.4x10^11 cm^-2

Identified zero field spin-splitting in p-type heterostructures

Observed persistent photoconductivity and isotropic mobility

Abstract

We implement metallic layers of Si-doped (110) GaAs as modulation doping in high mobility p-type heterostructures, changing to p-growth conditions for the doping layer alone. The strongly auto-compensated doping is first characterized in bulk samples, identifying the metal-insulator transition density and confirming classic hopping conduction in the insulating regime. To overcome the poor morphology inherent to Si p-type (110) growth, heterostructures are fabricated with only the modulation doping layer grown under p-type conditions. Such heterostructures show a hole mobility of 1.75x10^2 cm^2/Vs at density p=2.4x10^11 cm^-2. We identify the zero field spin-splitting characteristic of p-type heterostructures, but observe a remarkably isotropic mobility and a persistent photoconductivity unusual for p-heterojunctions grown using other doping techniques. This new modulated growth technique is particularly relevant for p-type cleaved-edge overgrowth and for III-V growth chambers where Si is the only dopant.