ELECTRICAL CHARACTERISTICS OF ZINC-DOPED INDIUM-PHOSPHIDE

We report on the electrical properties of Zn-doped (p-type) InP epilayers grown by metalorganic vapor-phase epitaxy. A detailed Hall transport model, accounting for the various scattering mechanisms in semiconductors and including valence-band degeneracy effects and inter- and intraband transitions, has been used for the analysis of the data. It provided excellent simultaneous agreement with the free-hole concentration and the mobility for Zn concentrations in the range of 7×1016-2×1018 cm-3. Those concentrations, for which the Hall factor was found close to 1, were confirmed by secondary-ion mass spectroscopy profiles. The binding energies of the samples were in the range of 42.7-26.2 meV and decreased with increasing Zn concentration. A simple approach, based on free-hole statistics, is proposed for the determination of the impurity concentrations of the lightly doped samples. An increased residual donor concentration, observed at a higher doping level, has been discussed.