IN0.5GA0.5AS/INALAS MODULATION-DOPED FIELD-EFFECT TRANSISTORS ON GAAS SUBSTRATES GROWN BY LOW-TEMPERATURE MOLECULAR-BEAM EPITAXY

We report on the lattice-mismatched growth and electrical properties of In0.5Ga0.5As/InAlAs modulation-doped heterostructures on GaAs substrates by molecular beam epitaxy using a wide-gap InAlAs graded buffer layer and low-temperature Molecular Beam Epitaxial growth at about 350-degrees-C. A drastic reduction in residual carrier accumulation has been achieved, and a high electron mobility at room temperature of 11100 cm2/V.s was obtained with an electron concentration of 3 x 10(12)/cm2. It was found that the cause of residual carrier accumulation is related to the growth interruption or temperature rise after the growth of the graded buffer layer. The fabricated Modulation-doped Field Effect Transistors showed low output conductance, good pinch-off characteristics and no kink effect. The higher transconductance of 270 mS/mm was also obtained.