Electrical Properties of Black Phosphorus Single Crystals Prepared by the Bismuth-Flux Method

Systematic measurement of the electrical transport phenomena of black phosphorus grown by the all-closed bismuth-flux method has been performed in the range from room temperature down to 0.5 K for the electrical resistivity and down to 1.5 K for the Hall effect and the magnetoresistance effect. These samples exhibited p-type conduction with two types of acceptors, of which activation energies were 26.1 meV and 11.8 meV, respectively. The effective concentrations of acceptors were typically 1.36×10 15 cm -3 for the deeper level and 0.44×10 15 cm -3 for the shallower level. The maximum of the Hall mobility was found to be 2×10 4 cm 2 /Vs around 20 K. A new observation of n-type conduction below about 7 K for some of these samples suggested the existence of a surface inversion layer as a channel of electron conduction.