Temperature dependence of time-resolved photoluminescence in mercuric iodide

Time-resolved photoluminescence (TRPL) of red mercuric iodide single crystal was measured from 10 K to 110 K. Several near band-gap exciton lines were found in 530 nm and a broad band was found at 630 rim. At near band-gap region photoluminescence comprises fast and slow decay components. Free excitons convert into bound excitons much more efficiently than the bound into the free so that non-radiative decay becomes dominant. At 10 K the dominant decay of bound excitons was radiation. With increasing temperature non-radiative decay became gradually dominant so that luminescent intensity of bound exciton line decreased and lifetime shortened quickly, especially from 20 K to 30 K. The TRPL experiment revealed that 630 nm hand originates from the radiative recombination of donor-acceptor pairs. The central wavelength of the band shifted toward shorter wavelength with increasing temperature and the intensity decay can be depicted as t(-n(r)). The recombination rate of the donor-acceptor pairs is dependent of wavelength and temperature.