MOVPE-grown Si-doped \b{eta}-(Al0.26Ga0.74)2O3 thin films and heterostructures

TL;DR

This paper demonstrates MOVPE growth of Si-doped -(Al0.26Ga0.74)2O3 thin films with high electron concentrations and explores modulation doping in heterostructures to achieve high sheet charge densities.

Contribution

It reports the first successful n-type degenerate doping and modulation doping in -(Al0.26Ga0.74)2O3/-Ga2O3 heterostructures grown by MOVPE, with detailed characterization.

Findings

Carrier concentration reaches 6x10^18 to 7.3x10^19 cm^-3.

Electron mobility ranges from 53 to 27 cm^2/V.s.

Heterostructures achieve a sheet charge of 2.3x10^12 cm^-2.

Abstract

We report on n-type degenerate doping in MOVPE grown \b{eta}-(Al0.26Ga0.74)2O3 epitaxial thin films and modulation doping in \b{eta}-(Al0.26Ga0.74)2O3/\b{eta}-Ga2O3 heterostructure. Alloy composition is confirmed using HRXRD measurements. Carrier concentration in the thin films is proportional to the silane molar flow. Room temperature hall measurements showed a high carrier concentration of 6x1018-7.3x1019 cm-3 with a corresponding electron mobility of 53-27 cm2/V.s in uniformly-doped \b{eta}-(Al0.26Ga0.74)2O3 layers. Modulation doping is used to realize a total electron sheet charge of 2.3x1012 cm-2 in a \b{eta}-(Al0.26Ga0.74)2O3/\b{eta}-Ga2O3 heterostructure using a uniformly-doped \b{eta}-(Al0.26Ga0.74)2O3 barrier layer and a thin spacer layer.