A.c. properties of semi-insulating InP

Abstract
The electrical conductivity of Fe-doped semi-insulating (SI) InP was measured between 77 K and 360 K over the frequency range 10 Hz-100 kHz. The conductivity at room temperature is of order 10−8 S cm−1, the activation energy being 0·64 eV. Below ∼250 K the conductivity is frequency dependent, varying with frequency as [sgrave](f)∼f s, where s∼1, and is only weakly thermally activated (∼0·01 eV). In the same frequency and temperature ranges we have also measured the permittivity of this material. Its value at 77K is ∼11.9 and its temperature coefficient amounts to 2·5×10−4K−1. In addition the permittivity has been investigated under high hydrostatic pressure up to 1 GPa. The pressure coefficient of permittivity has been found to be -2×10−2 GPa−1. The results obtained are discussed within the framework of a simple model.