High electron density β-(Al_(0.17)Ga_(0.83))_2O_3/Ga_2O_3 modulation doping using an ultra-thin (1 nm) spacer layer

摘要

This report discusses the design and demonstration of β-(Al_(0.17)Ga_(0.83))_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 the heterojunction interface was investigated in a β-(AlGa)_2O_3/Ga_2O_3 modulation doped structure. It is shown that this strategy enables a higher two-dimensional electron gas (2DEG) sheet charge density up to 4.7 × 10~(12)cm~(-2) with an effective mobility of 150 cm~2/V s. The presence of a degenerate 2DEG channel was confirmed by the measurement of a low temperature effective mobility of 375 cm~2/V s and the lack of carrier freeze out from low temperature capacitance voltage measurements. The electron density of 4.7 × 10~(12)cm~(-2) is the highest reported 2DEG density obtained without parallel conducting channels in a β-(Al_xGa_((1-x)))_2O_3/Ga_2O_3 heterostructure system.