Electrical and optical characterization of grain boundaries in polycrystalline cadmium telluride

Abstract

The optical and electrical properties of grain boundaries in n- and p-type CdTe have been investigated by analysis of single boundaries within bicrystals and of polycrystalline thin films. The grain-boundary parameters evaluated include the conductivity activation energy, the boundary diffusion potential, the energy distribution of grain-boundary states, the minority-carrier recombination velocity, the majority–carrier capture coefficient, and the optical cross section of grain-boundary states. Passivation experiments indicate that heat treatment in H2 or Li provide effective but temporary passivation in p-type CdTe, and that similar effects are found for heat treatment in air for n-type material.