Spectra of low-temperature photoluminescence in thin polycrystalline CdTe films

The band of intrinsic ($e$–$h$) radiation emission by the subsurface potential barriers of crystal grains and the edge doublet band arising as LO-phonon replicas of the $e$–$h$ band are observed in the spectra of the low-temperature (4.2 K) photoluminescence of fine-grained (with a grain size of $d_{\operatorname{cr}}\le$ 1 $\mu$m) CdTe films. Film doping with the In impurity results in quenching of the doublet band, while heat treatment leads to activation of the intrinsic band, a short-wavelength shift of the red boundary ($\Delta E_r$ = 16–29 meV) and the halfwidth modulation ($\Delta A$ = 6–17 meV) of which correlate with the height of micropotential barriers and the temperature of recombining hot photocarriers.