Mobility of Holes and Interaction between Acceptor Defects in ZnTe

Electrical transport studies in p-type ZnTe have confirmed that in the temperature range of about 80° to 500°K the hole mobility is principally limited by LO phonon scattering. An effective mass ratio of 0.6 gives the best fit to the experimental data. The highest mobility, 6500 cm2/V·sec at 35°K, was observed in a crystal with an active defect center concentration of 2×1015 cm−3. The ionization energy of the first charge state of a native acceptor, believed to be a Zn vacancy, was found to be ≥0.057±0.002 eV. Besides acting as shallow acceptor defects in ZnTe, the elements Li, Na, and P were found to promote the incorporation of substantial concentrations of native defects. High concentrations of Li, under excess Zn firing conditions, were observed to lead to highly compensated, low-mobility material, suggestive of self-compensation of the Li dopant.