MBE growth and characterization of MODFET heterostructures using pseudomorphic InGaAs or InAs/GaAs superlattice channels
We studied the influence of the growth temperature Ts and of the InGaAs quantum-well channel thickness dch 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 Å for an indium composition y = 0.25 of the channel. Significant improvements in sheet resistivity ϱs and in carrier concentration nso were obtained by using AlGaAs doped barriers on both sides of the pseudomorphic channel. We were thus able to obtain a 2DEG sheet density nso as high as 4.0×1012 cm-2 at 77 K, which is among the highest values reported for MODFET's on GaAs. Promising results were obtained on MODFET's using an (InAs)m (GaAs)n short period superlattice for the channel.