  Modulation-doped heterostructures are a key enabler for realizing high
mobility and better scaling properties for high performance transistors. We
report the realization of modulation-doped two-dimensional electron gas (2DEG)
at beta(Al0.2Ga0.8)2O3/ Ga2O3 heterojunction using silicon delta doping. The
formation of a 2DEG was confirmed using capacitance voltage measurements. A
modulation-doped 2DEG channel was used to realize a modulation-doped
field-effect transistor. The demonstration of modulation doping in the
beta-(Al0.2Ga0.8)2O3/ Ga2O3 material system could enable heterojunction devices
for high performance electronics.
