Hall effect and electrical resistivity measurements were carried out on und
oped InAs thin films grown by molecular-beam epitaxy directly on (001) GaP
substrates. The large lattice mismatch between these two compounds results
in a high density array of misfit dislocations at the heterointerface and t
hreading dislocations in the InAs epilayer. The threading dislocation densi
ty varies with epilayer thickness, with the largest proportion being presen
t near the heterointerface. This leads to variation of both the carrier con
centration and electron mobility with thickness. Consequently, a multilayer
analysis was used to interpret the transport data. This analysis yields a
temperature-independent carrier concentration, which indicates degenerate d
onor levels in this narrow band-gap material. Room temperature mobilities i
n excess of 10 000 cm(2)/V s were obtained for thick InAs layers despite di
slocation densities of 10(10) cm(-2). The relative insensitivity of the mob
ility to temperature suggests that temperature-independent scattering domin
ates over ionized impurity/defect and phonon scattering. (C) 2000 American
Institute of Physics. [S0021-8979(00)05603-6].