Ultrashort FETs formed by GaAs/AlGaAs MBE regrowth on a patterned δ doped GaAs layer

Abstract

We report on the successful molecular beam epitaxial (MBE) regrowth of a modulation doped GaAs/AlGaAs two-dimensional electron gas (2DEG) only 160 Å from a patterned GaAs mesa with a (1.5 K) mobility, without illumination, of 1×10 5 cm 2 V −1 s −1 at a carrier concentration of 5×10 11 cm −2. At a regrowth interface/2DEG separation of 300 Å, mobilities in excess of 1×10 6 cm 2 V −1 s −1 have been realised. By incorporating a Si delta doped layer in the first GaAs growth and using this to modulate the potential within a regrown 2DEG, we have demonstrated the growth of an ultra short FET.