High electron density ${\beta}-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doping using ultra-thin (1 nm) spacer layer

TL;DR

This paper demonstrates a novel ${eta}-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ heterostructure with an ultra-thin spacer layer that achieves record high electron sheet charge density and confirms the formation of a high-quality 2DEG channel.

Contribution

The study introduces a new modulation doping strategy with a 1 nm spacer layer to significantly enhance electron density in ${eta}-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ heterostructures.

Findings

Achieved a 2DEG sheet charge density of 6.1x10^12 cm^2.

Confirmed the presence of a degenerate 2DEG channel.

Reported high mobility of 147 cm^2/Vs at room temperature.

Abstract

We report on the design and demonstration of ${\beta}-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doped heterostructures to achieve high sheet charge density. The use of a thin spacer layer between the Si delta-doping and heterojunction interface was investigated in ${\beta}-(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ modulation doped structures. We find that that this strategy enables higher 2DEG sheet charge density up to 6.1x10^12 cm^2 with mobility of 147 cm^2/Vs. The presence of a degenerate 2DEG channel was confirmed by the measurement of low temperature effective mobility of 378 cm^2/V-s and a lack of carrier freeze out from low temperature capacitance voltage measurements. The electron density of 6.1x10^12 cm^2 is the highest reported sheet charge density obtained without parallel conduction channels in an $(Al_{0.18}Ga_{0.82})_2O_3/Ga_2O_3$ heterostructure system.