Surface electronic structure of p-InP using temperature-controlled surface photovoltage spectroscopy

Samples of p-InP (100) have been investigated using temperature-controlled surface photovoltage spectroscopy (T-SPS), in conjunction with time-resolved photoluminescence and intensity-resolved surface photovoltage measurements. In addition to the previously reported three gap states, attributed to excess surface P, adsorbed O, and Fe unintentional doping, T-SPS reveals a gap state, also attributed to Fe, situated 0.79 eV below the conduction-band minimum. The energy distribution of the latter state has been investigated by measuring its population as a function of temperature and shows good agreement with theory. A direct observation of the spectral blueshift of the InP band gap by T-SPS shows very good agreement with theory.