The Decay Behavior of Photo-Induced Electron Spin Resonance of Chromium in Zinc Sulfide

The decay behavior of photo-induced electron spin resonance of chromium in ZnS has been studied at temperatures between 77°K and 325°K with X-band. The Cr + ESR signal appeared under irradiation of light in a band centered around 3650Å. The simple calculations of photo-induced ESR signal have been made and compared with the experimental results. From these experimental results, it has been found that the decay behavior of Cr + ESR signals obey the bimolecular recombination process. The decay time constants above 250°K obey the exponential law (exp (- E t / k T )) and below 250°K they depart from this law. Especially, below 120°K these decay time constants are independent of temperature. In order to explain these temperature independent decay time constants below 120°K, the donor-acceptor pair recombination mechanism may be considered. On the other hand, the decay time constants above 250°K enable us to determine the value of trap depth ( E t =0.78 eV) which is in a reasonable agreement with the results of other methods.