Kk. Kim et al., The grain size effects on the photoluminescence of ZnO/alpha-Al2O3 grown by radio-frequency magnetron sputtering, J APPL PHYS, 87(7), 2000, pp. 3573-3575
ZnO thin films were epitaxially grown on alpha-Al2O3 (0001) substrate by ra
dio-frequency (rf) magnetron sputtering. Among the ZnO films deposited at 5
50 degrees C, the film deposited at 80 W has the narrowest full width half
maximum (FWHM) of x-ray diffraction (XRD) theta-rocking curve, 0.16 degrees
, indicating a highly c-axis oriented columnar structure. The FWHM of XRD t
heta-rocking curve of the ZnO film deposited at 120 W and 600 degrees C was
0.13 degrees with a minimum channeling yield, 4%-5%. In photoluminescence
(PL) measurement, only the sharp near band edge emission was observed at ro
om temperature (RT). The FWHM of PL peak was decreased from 133 to 89 meV a
s rf power increased from 80 to 120 W at 550 degrees C, and that of film de
posited at 120 W and 600 degrees C showed 76 meV which is lower value than
any other ever reported. These PL results were somewhat opposite to that of
XRD. From transmission electron microscopy analysis, grain size and defect
s were found to affect the PL properties. In this study, the PL property of
undoped ZnO thin films is discussed in terms of the crystalline structure
and the size of grain. (C) 2000 American Institute of Physics. [S0021-8979(
00)06303-9].