Résumé
We have applied a slow positron beam to study InN samples grown by metal-organic vapor-phase epitaxy with different V/III molar ratios (3300-24000) and at different growth temperatures (550-625 degrees C). Indium vacancies were identified in samples grown at V/III ratios below 4000. Their concentration is in the 10(17)cm(-3) range. No strong dependence of vacancy concentration on the molar ratio was observed. At low V/III ratios, however, In droplets and vacancy clusters are formed near the substrate interface. The elevated growth temperature enhances the In vacancy formation, possibly due to limited sticking of In on the growth surface close to the decomposition temperature. (c) 2006 American Institute of Physics.