Investigation of the Conduction Type of Nonstoichiometric Germanosilicate Glass Films

Knowledge of the dominant conduction type in dielectrics (electronic, hole, or bipolar) is critical for understanding transport phenomena in metal–insulator–semiconductor (MIS) structures. This paper presents a study of the conductivity type of nonstoichiometric germanosilicate glasses of varying composition (the silicon-to-germanium ratio varied from 0 to 3.25) for the first time. The method of minority carrier injection from a silicon substrate, combined with a comparative analysis of the current–voltage and capacitance–voltage characteristics (in darkness and under illumination) in the nonequilibrium depletion mode, showed that the germanosilicate glass film is characterized by bipolar conductivity. This conclusion is also confirmed by the results of measurements of the photovoltaic effect generated in the MIS-structures under illumination.