Electrical and Structural Characterization of In sub x Ga sub (1-x) As Strained Layers on GaAs

We present a study of the electrical and structural properties of lattice-mismatched In sub x Ga sub (1-x) As strained layers grown on GaAs(100). This strained system has been used in device structures because of the high carrier mobilities and high valence band discontinuities which may be obtained, but the inherent misfit strain is known to produce defects above some critical limit. We have grown, by Molecular Beam Epitaxy, structures with a p-type (Be) 8x10 sup (19) cm sup (-3) In sub x Ga sub (1-x) As layers, 200angstrom thick and with x = 0 to 0.50 in 0.05 steps, simulating the base of a heterojunction bipolar transistor. We correlate hole mobilities and sheet resistances with the microstructure of the strained layers as determined by Transmission Electron Microscopy (TEM).