Nature of the native deep localized defect recombination centers in the chalcopyrite and orthorhombic AgInS2

We studied the deep photoluminescence (PL) emission in polycrystalline chal copyrite and orthorhombic AgInS2. In both phases several PL bands were dete cted at 8 K. On the energy scale these deep PL bands are positioned accordi ng to a regular pattern. This is explained as being due to electron-hole re combination within very close deep donor-deep acceptor pairs, with differen t distances between donor and acceptor defects. The deep donor defect is an interstitial silver Ag-i and the native deep acceptor defect appears to be situated at the Ag or In place. The two different crystal modifications al so cause slightly different distances between donor and acceptor defects in the AgInS2 lattice and, as a result of this, different spectral positions of the deep PL bands. It is shown that these deep localized donor-acceptor pairs can be reasonably efficient radiative recombination centers up to dis tances of 5.3 Angstrom between the deep donor and the deep acceptor and, th us, up to six distinct deep PL bands are visible in AgInS2. The deep donor- deep acceptor pair model is confirmed also by the temperature quenching exp eriments and by the excitation power dependences. (C) 2000 American Institu te of Physics. [S0021-8979(00)01513-9].