Investigation of free and strained germanium whiskers at cryogenic temperatures

Results of the resistance studies on p-type germanium micro crystals grown in form of whiskers are presented. The crystals were brought to the vicinity of the metal-insulator transition (MIT) at liquid helium temperatures by doping with gallium and with some deep level impurities. A special technique has been developed to obtain these crystals anisotropically strained at cryogenic temperatures, so that both uniaxial tension and compression are achieved. The region adjacent to the MIT from both insulating and metallic side has been studied and some practical recommendations have been elaborated.