The Electrical Properties of Black Phosphorus

The electrical conductivity of black phosphorus has been measured as a function of temperature and pressure up to 350^∘{}C and 8000 kg/cm². The Hall constant of the same material has been measured as a function of temperature at atmospheric pressure. At low temperatures p-type impurity conduction is observed; at high temperatures the phosphorus is an intrinsic semiconductor with a gap width of 0.33 ev. The mobilities at 27^∘{}C are 350 cm²/volt sec and 220 cm²/volt sec for the holes and electrons, respectively. Application of hydrostatic pressure decreases the gap at a rate VdW/dV=8.3 ev. The results are also interpreted in terms of a two-dimensional semiconductor model.