High electron density <i>β</i>-(Al0.17Ga0.83)2O3/Ga2O3 modulation doping using an ultra-thin (1 nm) spacer layer
Nidhin Kurian Kalarickal, Zhanbo Xia, Joe F. McGlone, Yumo Liu, Wyatt Moore, Aaron R. Arehart, Steven A. Ringel, Siddharth Rajan
Abstract
This report discusses the design and demonstration of β-(Al0.17Ga0.83)2O3/Ga2O3 modulation doped heterostructures to achieve high sheet charge density. The use of a thin spacer layer between the Si delta-doping and the heterojunction interface was investigated in a β-(AlGa)2O3/Ga2O3 modulation doped structure. It is shown that this strategy enables a higher two-dimensional electron gas (2DEG) sheet charge density up to 4.7 × 1012 cm−2 with an effective mobility of 150 cm2/V s. The presence of a degenerate 2DEG channel was confirmed by the measurement of a low temperature effective mobility of 375 cm2/V s and the lack of carrier freeze out from low temperature capacitance voltage measurements. The electron density of 4.7 × 1012 cm−2 is the highest reported 2DEG density obtained without parallel conducting channels in a β-(AlxGa(1−x))2O3/Ga2O3 heterostructure system.