THE COULOMB GAP IN THE PHENOMENA OF NONLI NEAR SCREENING AND NONOHMICHOPPING CONDUCTIVITY

The hopping conductivity via the Coulomb gap states for a-Si<Mn> sampl es is studied in strong electric fields. All the features of the hoppi ng transport nonlinear effects predicted before are found experimental ly. The total spectrum of the field and temperature dependent conducti vity sigma(F, T) could be observed with studying the same sample. The decrease of sigma(F) is found with the growing of field. in the narrow field and temperature range the effect is so strong that the negative resistivity appears.