기상이동법으로 성장한 산화아연 나노막대의 포토루미네슨스 분석

ZnO nanorods were grown on Au-coated Si substrates by vapor phase transport (VPT) at the growth temperature of 600℃ using a mixture of zinc oxide and graphite powders as source material. Au thin films with the thickness of 5 nm were deposited by ion sputtering. Temperature-dependent photoluminescence (PL) was carried out to investigate the optical properties of the ZnO nanorods. Five peaks at 3.363, 3.327,3.296, 3.228, and 3.143 eV, corresponding to the free exciton (FX), neutral donor bound exciton (D^oX), first order longitudinal optical phonon replica of free exciton (FX-1LO), FX-2LO, and FX-3LO emissions, were obtained at low-temperature (10 K). The intensity of these peaks decreased and their position was red shifted with the increase in the temperature. The FX emission peak energy of the ZnO nanorods exhibited an anomalous behavior (red-blue-red shift) with the increase in temperature. This is also known as an “S-shaped”emission shift. The thermal activation energy for the exciton with increasing temperature in the ZnO nanorods is found to be about 26.6 meV; the values of Varshni’s empirical equation fitting parameters are =5×10^(−4) eV/K, β = 350 K, and E_g(0) = 3.364 eV.