The electrical properties of n-type semi-insulating indium phosphide

The electrical properties of semi-insulating n-type indium phosphide single crystals which have been pulled from the melt by the liquid-encapsulation technique are reported. Measurements of thermal activation energies for both ohmic and space-charge limited conduction over a broad temperature range have enabled the deduction of both depth and concentration of the localized levels in Cr-doped material. One dominant level is situated approximately 0.20 eV from the conduction band. A deeper level at 0.54 eV is attributed to the Cr impurity in the crystals. Data for iron-doped InP show that this type of crystal may also be suitable as an epitaxial substrate material.