SPIN-FLIP RAMAN-SCATTERING STUDIES OF POSTGROWTH ANNEALED P-TYPE NITROGEN-DOPED ZINC SELENIDE

Spin-flip Raman scattering (SFRS) studies of post-growth annealed p-ty pe nitrogen-doped zinc selenide grown by photoassisted metallo-organic vapour phase epitaxy (MOVPE) are presented. Four pieces from the same parent structure were subjected to annealing times between 0 and 60 m in in a nitrogen atmosphere at a temperature of 500 degrees C. The cha nges in net nitrogen acceptor concentration were determined via capaci tance-voltage measurements and the samples studied by photoluminescenc e and SFRS. The results indicate that an annealing time of 30 min yiel ds the greatest net acceptor concentration. However, whilst the sample annealed for this time showed the strongest SFRS signals due to neutr al accepters, it also gave the strongest SFRS signal from the deep don ors that act as compensating centres. The results suggest that the num ber of active accepters increases initially on annealing but decreases as annealing continues; it also appears that the concentration of acc epters cannot be raised by annealing without a simultaneous increase i n the concentration of the deep donors. The behaviour can be accounted for by the activation (at short annealing times) of accepters which w ere passivated by hydrogen during growth and (at longer annealing time s and higher annealing temperatures) by the diffusion of defects.