HOPPING SPECTROSCOPY IN DOPED GERMANIUM NEAR THE METAL-INSULATOR-TRANSITION

The density of states (DOS) in the vicinity of the Fermi level control s all transport phenomena at low temperatures near the metal-insulator transition (MIT). The well-known method for DOS-determination on the metallic side of the MIT, the so-called ''tunneling spectroscopy''. is inapplicable on the insulating side because of the high sample resist ance at low temperatures. In this work a new method for DOS-determinat ion on the insulating side is presented. The method is based on the me asurements of variable range hopping (VRH) resistance in magnetic fiel ds. By analogy this method can be called ''hopping spectroscopy''.