Conduction and crystallization of amorphous cuprous iodide

Abstract

Cuprous iodide is an electronic conductor below about 500 K. Dielectric measurements on thin films prepared at 80 K show d.c. conductivity losses and semiconductor behaviour but no evidence of space-charge polarization which might arise from blocking of charge-carriers at the electrodes. Athermal conductivity measurements show crystallization occurring over a narrow temperature range 105–115 K. Isothermal annealing within this range is in accordance with the generalized Johnson-Mehl equation, volume transformed ∝{1—exp—kt)ⁿ }, but with an experimental value of n=1. This cannot be explained by conventional nucleation and growth processes and a model is proposed which involves the sudden formation of crystallites of small but finite size.