PHOTOLUMINESCENCE AND RAMAN STUDIES OF IN HIGH-QUALITY CDTE-I EPILAYERS

Low-temperature photoluminescence (PL) studies of iodine-doped CdTe ep ilayers have been performed. A compensating acceptor center which give s rise to deep-level PL emission at 1.491 eV is identified. From selec tive excitation PL studies, we assign this 1.491 eV line to the recomb ination of an associate donor-acceptor close pair, consisting of neare st neighbor substitutional sodium and iodine atoms (Na-cd - I-Te). Thi s neutral defect complex has a localized mode of 36.5 meV, which is mu ch larger than the bulk CdTe lattice mode of 21.3 meV. The electronic energy level associated with this defect is 115 meV below the conducti on band. Also, we use a combination of selective excitation PL and Ram an spectroscopies to determine the ionization energy of the isolated s hallow iodine donor (I-Te) in CdTe. We find that the donor binding ene rgy of this anion-site hydrogenic donor is 15.0 (+/- 0.2) meV.