Temperature-dependent exciton luminescence from an Au-nanopattern–coated ZnCdO film

¹ Department of Materials Science and Engineering, National University of Singapore - Singapore 117576, Singapore
² Department of Physics, Xiamen University - Xiamen 361005, Fujian, PRC
³ Data Storage Institute, A*STAR (Agency for Science, Technology and Research) - 5 Engineering Drive 1, Singapore 117608, Singapore
⁴ Department of Electrical and Computer Engineering, National University of Singapore Singapore 117576, Singapore
⁵ Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) 3 Research Link, Singapore 117602, Singapore
⁶ Du Pont Apollo Limited - No. 8 Science Park West Ave., Hong Kong Science Park, Pak Shek Kok, New Territories, Hong Kong

^(a) wfyang@yahoo.com
^(b) msegongh@nus.edu.sg (corresponding author)

Received: 27 March 2012
Accepted: 25 June 2012

Abstract

Surface plasmon (SP) mediated emission from highly ordered Au-nanopattern–capped ZnCdO film has been studied by temperature-dependent photoluminescence (TDPL) from 10 to 300 K. It is found that the bandgap emission from Au-capped ZnCdO is stronger than that of bare ZnCdO throughout the entire temperature range owing to SP coupling and surface modification. The TDPLs of ZnCdO films with and without Au coatings exhibit an inconspicuous S-shape in the plot of emission peak energy (E_p) vs. temperature, signifying a weak carrier localization effect: E_p redshifts in the temperature range of 10–80 K, blueshifts in the range 80–140 K, and redshifts again in the range 140–300 K. It is interesting to find that the temperature-dependent behavior of the enhancement ratio can be divided into three temperature ranges. In the low- and high-temperature ranges, the enhancement ratio is not significantly changed with temperature. However, in the medium-temperature range, the enhancement ratio increases monotonically with temperature due to the excitons delocalization from the potential minima. These results indicate that excitons delocalization is an important prerequisite of the efficient plasmonic enhancement for SP mediated emission from ZnCdO system.