ATOMIC DISTRIBUTION IN ZNXCD1-XGEP2 SEMICONDUCTOR ALLOYS - P-31 AND CD-113 MAGIC-ANGLE SPINNING, P-31 SPIN-ECHO, AND P-31-CD-113 HETERONUCLEAR DOUBLE QUANTUM FILTERING MAS-NMR STUDIES

Cation substitution in the ZnxCd1-xGeP2 (0 less-than-or-equal-to x less-than-or-equal-to 1) system results in homogeneous solid solutions which crystallize in the chalcopyrite structure. The distribution of local (nearest-neighbor) environments in these materials has been examined on the basis of complementary solid-state NMR experiments, including P-31 and Cd-113 magic-angle spinning (MAS), P-31 spin-echo, and P-31-Cd-113 heteronuclear double quantum filtering (HDQF) MAS-NMR. Cd-113 and P-31 MAS-NMR spectra show poorly resolved resonances whose chemical shifts change monotonically with increasing x. P-31 spin-echo decay data reveal that the P-31-P-31 homonuclear dipole coupling is stronger than calculated based solely on inhomogeneous dipolar broadening. P-31-Cd-113 HDQF MAS-NMR experiments offer site discrimination attributable to specific local nearest-neighbor configurations and thus provide useful peak deconvolution constraints. The results obtained using these techniques suggest a nonstatistical population distribution of the nearest-neighbor environments, in which mixed PGe2CdZn sites are disfavored.