Wavelength dependence of laser-induced phase transformations in semiconductor quantum dots
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We study the effect of wavelength on the laser-induced phase transformation in semiconductor quantum dots. In our earlier report [Yakovlev et al., Appl. Phys. Lett. 76, 2050 (2000)], we discovered that a nanosecond pulse of 532 nm radiation results in a phase transformation of CdS nanocrystals from an orthorhombic to cubic phase. In this study, we find that irradiation with the pulse of a different wavelength (355 nm) results in a completely different transformation to a hexagonal wurtzite phase and a significant broadening of nanocrystal size distribution. The nanocrystal stoichiometry remained unchanged by the laser irradiation, as verified by energy dispersive x-ray spectroscopy. 2001 American Institute of Physics.