CAP AND CAPLESS ANNEALING OF FE-IMPLANTED INGAAS

The distribution of Fe implanted at medium (1-4 X 10(14) cm-2) and low (2 X 10(12) cm-2) doses into InGaAs and annealed with or without a cap is investigated and the degree of compensation of such implanted regions is assessed. Secondary ion mass spectrometry profiles of low dose implanted Fe reveal a substantial role of the capping layer. Fe concentrations below as well as above the estimated metal vacancy concentration produced by implantation are observed. The effect of the cap strongly depends on the wet chemical surface preparation before insulator deposition. A correlation of the magnitude of the Fe accumulation at the InGaAs surface with defect related photoluminescence intensity is established. On the basis of the substitutional-interstitial diffusion model the barrier effects of the various caps for host and dopant atoms are analyzed. The best semi-insulating properties were obtained for plasma enhanced chemical vapor deposition SiO2 caped samples using a H2SO4:H2O2:H2O=1:1:125 surface preparation before deposition resulting in a 53% incorporation of Fe. A high electrical activation is proved directly by capacity-voltage profiles.