Temperature dependent photoluminescence studies of ZnO thin film grown on (1 1 1) YSZ substrate

ZnO thin films were grown on c-sapphire and YSZ (1 1 1) substrates by pulsed laser deposition. The rocking curve of ZnO films grown on YSZ (1 1 1) had full width at half maximum (FWHM) of 0.03°, similar to that of single crystal ZnO. Neutral donor bound exciton (D0X) and its phonon replicas at equidistant of 72 (D0X-LO) and 144 meV and (D0X-2LO) and free exciton (FX) peaks were observed in low temperature photoluminescence (PL). The D0X and its phonon replicas peak intensity decreased while the FX and its phonon replicas (FX-LO and FX-LO2) peak intensity increased when the temperature increased up to 120 K. The estimated activation energies of D0X and FX are 17.5 and 25 meV, respectively. Room temperature (RT) PL line width of FX was ∼77 meV only. Narrow FWHM of the rocking curve together with narrow RT PL line width of ZnO thin films grown on YSZ (1 1 1) is an indication of high crystalline and optical quality of the films.