The role of different charge states of impurity ions in photoconductivity of insulators

Abstract

The results of experimental studies of stationary photoconductivity of single-crystal Al₂O₃:Ti³⁺, Y₃Al₅O₁₂:Ti³⁺, YAlO₃:Ti³⁺, and Li₂Ge₇O₁₅:Cr³⁺ where the photocurrent is induced by two-step photoionization of 3d-ions via intermediate metastable state, are presented. The dependence of stationary two-step excited photocurrent j on optical pumping density P (j∼Pⁿ, n = 2, 3/2 for different cases) appears to be very informative for studies of all steps of photoelectric processes including photoionization of 3d-ions, capture by traps and release of photocarriers and their recombination.

Key Words:

• Key words: doped insulators
• Li₂Ge₇O₁₅:Cr³⁺
• photoconductivity
• two step photoionization
• trapped carriers.