Reverse Doping Asymmetry in Semiconductor Thin Films Using External Voltage

TL;DR

This paper proposes a theoretical method to reverse doping asymmetry in semiconductor thin films by applying external voltage, enabling control over n- and p-type doping during growth, demonstrated on zinc oxide.

Contribution

It introduces a voltage-assisted doping approach that can tune band edges and reverse doping asymmetry, applicable across various materials and growth conditions.

Findings

Suppresses spontaneous n-type defects by around four orders

Successfully induces p-type zinc oxide at low acceptor levels

Approach is insensitive to material and defect variations

Abstract

Doping asymmetry is a notable phenomenon with semiconductors and a particularly longstanding challenge limiting the applications of most wide-band-gap semiconductors, which are inherent of spontaneous heavy n- or p-type doping because of their extreme band edges. This study theoretically shows that by applying a proper external voltage on materials during their growth or doping processes, we can largely tune the band edges and consequently reverse the doping asymmetry in semiconductor thin films. We take zinc oxide as a touchstone and computationally demonstrate that this voltage-assisted-doping approach efficiently suppresses the spontaneous n-type defects by around four orders under three distinct growth conditions and successfully generates p-type zinc oxide up to the lowest acceptor levels. The proposed approach is insensitive to materials, growth conditions, or defects origins, and thus offers a general solution to the doping asymmetry in semiconductor thin films.