Local doping of an oxide semiconductor by voltage-driven splitting of anti-Frenkel defects

TL;DR

This paper demonstrates voltage-driven local doping in layered oxide semiconductors through anti-Frenkel defect splitting, enabling nanoscale p- and n-type regions with potential applications in transient electronics.

Contribution

It introduces a novel method for local acceptor and donor doping in oxides via defect splitting under voltage, combining experimental and theoretical techniques.

Findings

Voltage-driven defect splitting enables local doping.

Nanoscale p- and n-type regions are stable for days.

Defect mobility allows patterning of oxide semiconductors.

Abstract

Layered oxides exhibit high ionic mobility and chemical flexibility, attracting interest as cathode materials for lithium-ion batteries and the pairing of hydrogen production and carbon capture. Recently, layered oxides emerged as highly tunable semiconductors. For example, by introducing anti-Frenkel defects, the electronic hopping conductance in hexagonal manganites was increased locally by orders of magnitude. Here, we demonstrate local acceptor and donor doping in Er(Mn,Ti)O$_3$, facilitated by the splitting of such anti-Frenkel defects under applied d.c. voltage. By combining density functional theory calculations, scanning probe microscopy, atom probe tomography, and scanning transmission electron microscopy, we show that the oxygen defects readily move through the layered crystal structure, leading to nano-sized interstitial-rich (p-type) and vacancy-rich (n-type) regions. The resulting pattern is comparable to dipolar npn-junctions and stable on the timescale of days. Our findings reveal the possibility of temporarily functionalizing oxide semiconductors at the nanoscale, giving additional opportunities for the field of oxide electronics and the development of transient electronics in general.