Photoluminescence of Defect-Exciton Complexes in II-VI Compounds

Abstract

We have examined band-edge fluorescent emission spectra in various II-VI compounds at 4°K with the objective of establishing correlations between the presence of specific spectra and the presence of specific defects. The basis for such correlations is the proven existence of radiative recombination from excitons bound to defects, 1 " 3 and the expectation that such mechanisms can account for much of the plethora of band-edge spectra observed. We have found evidence for a simple relationship governing such correlations for this family of compounds-a significant extension of Haynes's observations 1 in silicon. Figure 1 (insert) illustrates the procedure employed for acceptor defects. We have attempted, by purification and subsequent introduction of acceptor defects, to obtain samples which exhibit a dominant emission process of near-band-gap energy at 4°K correlated with the presence of a dominant emission process 0.200 0,050 0010 0005 0002,

Chemistry of defect induced photoluminescence in chalcopyrites: The case of CuAlS2

“…For instance, PL experiments on II-IV compounds yielded PL emissions that were interpreted as resulting from an exciton-neutral-defect complex. [43][44][45] These results showed that the E BE of the exciton-neutral-defect complex is about 0.20 times the E BE of the corresponding radiative recombination process of the associated defect (E BE =0.20ε(D, q/q )). Sharma and Rodriguez 46 and Atzmüller et.al.…”

Photoconductivity and photoluminescence in chemically deposited films of CdSSe:CdCl2,Ho

“…Bube and co−workers [1,2] have extensively studied the photoconduction properties of CdS and CdSe single crystals, like sensitivity, IR quenching, temperature dependence, super linearity and slow growth of photocurrent. Similarly, the PL edge emission was intensively investigated in CdS crystals by several workers [3][4][5] and was associated with the excitonic transitions involving free excitons or defect−exciton complexes [6]. However, in recent years, the effect of alloying of CdS, CdSe, and other II-VI group compounds on the PC and PL properties has become a field of much interest.…”

Relation of recombination radiation spectra to the concentration of structure defects in CdS single crystals

“…with seven pulses of P = 30 MW/cni2). (1) spectrum of the initial crystal; (2) to (7) after irradiation with laser pulses of P = 20, 30, 40, 60, 80, and 100MW/cm2, respectively; (8) and (9) after two and three pulses with P = 100 MW/cm2 (1) spectrum of the initial crystal CdS; (2) to (5) after 1,2, 7, and 15 pulses with P = 30 MW/cmZ; (6) after etching of a 1 pm layer Two CdS crystals with different donor or acceptor impurity concentrations, labelled No. 1 or 2, were used.…”

“…Thus, laser illumination results in the formation of native point defects, mostly of donor type. The energy depth of the donor centres (Ed) which govern the growth of I,, can be determined from which is of order 0.20 in donor-doped n-type 11-VI coinpounds [6], where E,, -EI, is the binding energy of an exciton to a donor centre. The value of Ed was found to be 0.038 eV.…”