EPR AND LUMINESCENCE STUDIES OF ER+3 IN ACCEPTOR-DOPED ZNTE

Er+3 can be incorporated in the ZnTe lattice in significant concentrations by co-doping with an acceptor species. From EPR studies at 4°K, the symmetries of the dominant sites in ZnTe (Er,P) are trigonal (gII=1.254, g=9.469) and cubic (g=5.93). For ZnTe (Er,Li) crystals, the same cubic site is observed, but the dominant site has trigonal symmetry (gII=4.066, g=8.068). Thermal treatments which are known to remove Li from electrically active centers in ZnTe greatly increase the strength of the cubic spectrum and greatly reduce the strength of the trigonal spectrum. The sharp-line emission observed in photoluminescence occurs in the region 663 nm and represents a transition from F924 to the ground state of Er+3. This sharp-line emission is weakest in those samples in which the cubic EPR spectrum is the strongest, which indicates that Er+3 on a substitutional Zn site with nonlocal charge compensation is not an efficient radiative-recombination center for rare-earth emission. Rare-earth electroluminescence at 77°K is observed from diodes fabricated from ZnTe(Er,Li) and ZnTe(Er,P) substrates. © 1969 The American Physical Society.