X-ray reflectivity determination of interface roughness correlated with transport properties of (AlGa)As/GaAs high electron mobility transistor devices

To explore the role of interface scattering in high electron mobility transistor (HEMT) device performance, a series of samples consisting of both a superlattice and a HEMT structure were grown by molecular beam epitaxy (MBE) at temperatures ranging from 500 to 630 °C. Hall measurements indicate a trend toward higher mobilities in samples grown at higher temperatures. Subsequent x-ray reflectivity measurements were made, and the data were fitted by least-squares refinement of a calculated reflectivity curve determined from a model of the sample structure to obtain the composition profile along the growth direction. These results indicate smoother interfaces for the samples with higher mobilities.