I─V characteristics of Bi4Ge3O12─Mn crystals in the unipolar injection mode

Abstract

Current-voltage relations in Bi₄Ge₃O₁₂ ─ Mn crystals were measured under the conditions of unipolar injection of charge carriers. The characteristics obtained for electrons and holes are different. I-V curves in the case of electron injection contain ohmic, quadratic regions and regions of a sharp increase in current. This indicates the formation of a space charge enriched in electrons. The values of conductivity, effective drift mobility, and electron concentration calculated at different temperatures are close to the values obtained for pure crystals. In the case of hole injection I-V curves are characterized by the presence of sublinear regions. It is assumed that injection of the holes causes the formation of a space charge layer depleted in electrons due to the recombination. It is shown that doping with manganese does not change the nature of conductivity in bismuth germanate crystals and strongly affects the recombination processes.