a Study of Defects and Their Roles in Recombination Process in Semiconductors Using Odmr.

This dissertation describes an experimental investigation of fundamental properties of defects in semiconductors, using optical detection of magnetic resonance (ODMR). The technique provides microscopic identification of the defects as well as the electronic structure of their excited states and the mechanisms of recombination processes in which the defects are involved. Two distinct recombination processes have been revealed through the investigation: distant donor-acceptor (DA) pair recombination and bound-exciton (BE) recombination (a localized spin triplet system). The former provides a unique way to study individual donors or acceptors in their uncompensated charge states. Defects observed in this category include deep acceptor {the zinc vacancy and its associates such as the self-activated (SA) centers in ZnS and ZnSe}, deep donors (the antisite defect, P(,Ga), and O(,P) related centers in GaP), shallow acceptors (Zn(,Ga) in GaP under uniaxial stress and Al in SiC), and shallow donors (N in SiC, etc.). Defects detected through bound-exciton decay luminescence include Ti in SiC, C-Si -C in radiation damaged Si, the antisite related (P(,Ga)(.)Y(,P)) defect in GaP, and many other spin triplet defects in electron irradiated SiC.