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 2 eV at room temperature is obtained while the typical bandgap transition energy of ZnSe is 2:7 eV. When the temperature is reduced to 150 K, the peak wavelength shifts to 2:3 eV with yellowish emission and then blue emission with the peak at 2:7 eV at temperature less than 50 K. The overall wavelength shift of 700 meV 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 energy of 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.

Photoluminescence and surface photovoltage properties of ZnSe nanoribbons

“…The DD band can be fitted into three sub-bands, respectively, centered at 623 nm (DD1), 563 nm (DD2) and 525 nm (DD3) (the dash lines in spectrum 7), which agrees well with the previous reports [15][16][17][18]. The previous researches about temperature-dependent PL reveal the thermally activated dynamic processes of photogenerated electrons transfer from shallower to deeper energy states [17,19,26]. Here, at low excitation intensity, the dominant band of DD1 emission in the PL spectrum (spectrum 1) indicates the recombination of photogenerated carriers from DD1 states prior to the shallower states and conduction band, due to the thermal activated relaxation process of the photogenerated electrons.…”

Spin–exciton interaction and related micro-photoluminescence spectra of ZnSe:Mn DMS nanoribbon

“…Zinc selenide, an II-VI semiconductor with direct band gap of ∼2.7 eV at room temperature, has excellent optical properties and has potential application in light emitting diodes, lasers, and other short wavelength optoelectronic devices [18][19][20]. Compared with ZnO and ZnS, ZnSe has a higher valence band according to the calculation of band offsets [21].…”