Field-Induced Conductivity Changes in Germanium

Abstract

Variations in the conductance of a germanium filament due to an electric field normal to the surface were measured for fields up to ${10}^{5}$ volts/cm. Observation of a minimum in the conductance curve makes it possible to calculate charge in surface states as a function of surface potential. Information of this sort obtained with several gaseous ambients is compared with the Brattain-Bardeen observations on contact potential. Measurements as a function of temperature down to 170\ifmmode^\circ\else\textdegree\fi{}K give information about properties of "fast" surface states. Phase shift loops observed at frequencies around a kilocycle are interpreted in terms of minority carrier lifetime. Phase shift loops at low temperatures are believed to be due to traps.