ELECTRICAL-CONDUCTIVITY OF BLACK PHOSPHORUS-GERMANIUM COMPOUND

Single crystals of a new material, black phosphorus doped with germanium, have been prepared by a bismuth-flux method. Germanium atoms are incorporated into the black phosphorus in 2 to 4 atomic percent. The resistivity is reduced by two to three orders (rho = 6 x 10(-3) OMEGA cm) compared with the pure black phosphorus, and its temperature dependence is metallic at low temperatures. There is no magnetoresistance up to 12 T at 0.6 K in striking contrast to the pure black phosphorus which shows negative magnetoresistance in this region. The crystal lattice constants decrease with germanium doping, especially in the interlayer direction. These facts indicate the enhanced three dimensionality with germanium doping.