MBE growth and characterization of MODFET heterostructures using pseudomorphic InGaAs or InAs/GaAs superlattice channels

We studied the influence of the growth temperature T s and of the InGaAs quantum-well channel thickness d ch on the 300 and 77 K Hall electrical properties of pseudomorphic MODFET-type heterostructures grown by molecular-beam epitaxy (MBE). In agreement with Nguyen et al., we find an optimum channel thickness of 90 A for an indium composition y =0.25 of the channel. Significant improvements in sheet resistivity p s and in carrier concentration n so were obtained by using AlGaAs doped barriers on both sides of the pseudomorphic channel. We were thus able to obtain a 2DEG sheet density n so as high as 4.0×10 12 cm?2 at 77 K, which is among the highest values reported for MODFETs on GaAs. Promising results were obtained on MODFET's using an (InAs) m (GaAs) n short period superlattice for the channel.