The Role of Spatial Potential Fluctuations in the Shape of the PL Bands of Multinary Semiconductor Compounds

Abstract

Photoluminescence (PL) measurements of (x \ 0.5) single CuIn 1~x Ga x Se 2 crystals grown by the vertical Bridgmann technique were made at temperatures ranging from 11 K to 200 K and with various excitation powers. At low temperatures only one asymmetric PL band (BT-band) is present at 1.23 eV. It has a steeper decline on the high-energy side and nearly temperature independent low-energy side. At higher temperatures (T [ 140 K) the BB-band becomes visible at 1.31 eV. We used an asymmetric double sigmoidal function to Ðt the experimental PL spectra. The results of this Ðtting can be interpreted to show the presence of spatial potential Ñuctuations in our samples. Observed dependencies would seem to reveal that the BT band is indeed connected with the recombination of a free electron with a localized hole. It is shown that these relatively deep localized states are probably formed due to potential Ñuctuations in highly compensated material and are not connected with any particular acceptor defect. We show that this model conforms to most of the discovered dependencies.

A photoluminescence study of CuInSe2 single crystals ion implanted with 5 keV hydrogen

“…CuInSe 2 contains both donors and acceptors showing p-type conductivity if the concentration of acceptors is higher than that of donors. Because its electrons are lighter than holes the high doping condition is usually achieved for donors but not achieved for acceptors [18].…”

“…To determine and improve the accuracy of the analysis the experimental spectra were fitted with the empirical double sigmoidal function proposed in ref. [18]:…”

Comparative study of the luminescence and intrinsic point defects in the kesterite Cu2ZnSnS4and chalcopyrite Cu(In,Ga)Se2Romero1, Du2, Teeter3 et al. 2011Phys. Rev. B20351220View full textAdd to dashboardCite

“…The luminescence of Cu-poor CIGS has been extensively investigated by other authors [15,16] and here we summarize the aspects most relevant to our comparative study of chalcopyrites and kesterites. This is better described by considering first the point defect structure of chalcopyrites under (Fig.…”

Influence of electric field on photoluminescence of Cu(In,Ga)Se2-based solar cells

“…The PL spectrum of the Cu poor material, commonly used in solar cells, exhibits very broad peaks, often merging into one fea− tureless maximum. The intensity and temperature dependence of some of these PL maxima points towards an explanation being the fluctuating potentials in highly compensated, defected material [10][11][12][13].…”