ELECTRICAL-PROPERTIES OF INGAP DOPED WITH SI

We measured Hall concentration n in InGaP:Si epitaxial layers grown by MBE as a function of pressure P up to 2 GPa and of temperature T from 77 to 300 K. We interpreted our results in terms of the broad distrib ution of impurity states resonant with the conduction band. From the l ow-temperature n(P) dependence we can directly obtain the total densit y of impurity states around the Fermi level rho(E-F). The Fermi level can be shifted with respect to impurity states by applying pressure an d by using samples with different n. In this way we obtain rho(E) in a wide energy range. We discuss the possible reasons for the observed b road distribution of rho(E).