STRUCTURAL PHASE-BEHAVIOR IN II-VI SEMICONDUCTOR NANOPARTICLES

Cubic structured CdS, CdSe, and CdTe, II-VI semiconductor nanoparticle s have been synthesized using aqueous solution precipitation at room t emperature. The ''as-prepared'' particles have a size of about 30 Angs trom. Thermal annealing causes (a) an increase in particle size; (b) a structural transition from the cubic to the bulk, hexagonal structure for CdS and CdSe; and (c) no structural transition for CdTe. The unex pected cubic phase for small particles of CdS and CdSe may be due to e ither metastability or an equilibrium surface effect. The latter would imply a strong correlation between structure and the size and surface properties, and that there is a minimum size for hexagonal phase stab ility. (C) 1995 American Institute of Physics.