High electron mobility in pseudomorphic modulation-doped In0.75Ga0.25As/InAlAs heterostructures achieved with growth interruptions

Growth interruptions under cation stabilization have been used to smooth the two interfaces defining the pseudomorphic channel layer of InAlAs/In0.75Ga0.25As/InAlAs heterostructures grown on InP. This leads to a 4 K electron mobility as high as 170 000 cm2/V s, due to the reduction of interface roughness scattering. This structure is used as a reference (‘‘zero’’ interface roughness) for a model to determine the influence of interface roughness scattering on the electron mobility as a function of the channel indium fraction (xIn=0.53, 0.65, and 0.75) in heterostructures grown without growth interruption. It is shown that the interface roughness scattering decreases with increasing indium concentration of the channel in the range 0.53–0.65 and saturates beyond xIn=0.65.