Enhanced Electron Mobility in the Inverted High Electron Mobility Transistor Structure by Two-Step Molecular Beam Epitaxy (MBE) Growth

Abstract

Electron mobility dependence on molecular beam epitaxy (MBE) growth temperature for the channel layer in inverted high electron mobility transistors (HEMTs) has been investigated. 77 K 2-DEG mobility is increased up to 101200 cm2·V-1·s-1, even with a thin spacer layer (8 nm) by raising the growth temperature to 660° C, after growing the underlying n-AlGaAs:Si at 450° C. Its mobility is 43% higher than that of a continuously grown sample whose channel layer was grown at 450° C. With a thicker spacer layer (25 nm), two-step MBE growth facilitated very high mobility of 165000 cm2·V-1·s-1 at 77 K and 550000 cm2·V-1·s-1 at 10 K.