Photoluminescence of high optical quality CdS:Dy thin films deposited by close-spaced vacuum sublimation.

CdS:Dy polycrystalline films were deposited by close-spaced vacuum sublimation (CSVS) method using glass slides as substrates. The films are highly dispersed with the grain size from smaller than 0.1 μm to 1.0 μm. The CdS:Dy films are n-type and only correspond to single wurtzite phase. The crystallites are preferentially oriented with (002) planes parallel to the substrate surface. Analysis of PL spectra, caused by the emission of donor-acceptor pairs lets us determine the nature and energy structure of the intrinsic defects and residual impurities in the films. It is important to note that the PL and reflection spectra observe the narrow lines of bound and free excitons. This allows us to found bandgaps of these films quite accurately. A correlation between optical and structural properties was established. The results of the structural and PL measurements showed that the CdS:Dy polycrystalline films are of highly crystal and optical quality. [ABSTRACT FROM AUTHOR]