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

We report on the successful molecular beam epitaxial (MBE) regrowth of a modulation doped GaAs/AlGaAs two-dimensional electron gas (2DEG) only 160 Angstrom from a patterned GaAs mesa with a (1.5 K) mobility, without illumination, of 1 x 10(5) cm(2) V-1 s(-1) at a carrier concentration of 5 x 10(11) cm(-2). At a regrowth interface/2DEG separation of 300 Angstrom, mobilities in excess of 1 x 10(6) cm2 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. (C) 1999 Elsevier Science B.V. All rights reserved.