Largely extended light-emission shift of ZnSe nanostructures with temperature

Abstract

ZnSe nanowires and nanobelts with zinc blende structure have been synthesized. The morphology and the growth mechanisms of the ZnSe nanostructures will be discussed. From the photoluminescence (PL) of the ZnSe nanostructures, it is interesting to note that red color emission with only a single peak at the photon energy of 2eV at room temperature is obtained while the typical bandgap transition energy of ZnSe is 2.7eV. When the temperature is reduced to 150K, the peak wavelength shifts to 2.3eV with yellowish emission and then blue emission with the peak at 2.7eV at temperature less than 50K. The overall wavelength shift of 700meV is obtained as compared to the conventional ZnSe of about 100 meV (i.e., sevenfold extension). The ZnSe nanostructures with enhanced wavelength shift can potentially function as visible light temperature- indicator. The color change from red to yellowish and then to blue is large enough for the nanostructures to be used for temperature-sensing applications. The details of PL spectra of ZnSe at various temperatures are studied from (i) the spectral profile, (ii) the half-width half-maximum, and (iii) the peak photon energyof each of the emission centers. The results show that the simplified configuration coordinate model can be used to describe the emission spectra, and the frequency of the local vibrational mode of the emission centers is determined. © 2011 Optical Society of America.