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 dcr ≤ 1 µm) 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 (ΔEr = 16–29 meV) and the halfwidth modulation (ΔA = 6–17 meV) of which correlate with the height of micropotential barriers and the temperature of recombining hot photocarriers.