Sputtering power dependence of structure and photoluminescence of ZnO on 6H–SiC

Abstract

High quality ZnO/SiC composite structure have great potential in integrating surface acoustic wave devices with semiconductor devices. To achieve high quality ZnO on 6H–SiC, ZnO films were sputtered with various power by radio frequency magnetron sputtering. It was observed that all films possessed hexagonal wurtzite crystal structure with c-axis orientation. With the increasing of sputtering power, the growth rate rose steadily while the in-plane orientation of ZnO thin films gradually degraded. The FWHM of rocking curve, stress, intensity of visible emission reached a maximum at 125 W and then decreased with sputtering power further increasing. Films deposited at 75 W exhibited narrowest rocking curve of 1.44°, lowest visible emission and stress with orientation relationship: $${(0002)_{{\text{ZnO}}}}\parallel {(0006)_{{\text{SiC}}}}$$ and $${[11\bar {2}0]_{{\text{ZnO}}}}\parallel {[11\bar {2}0]_{{\text{SiC}}}}$$ . TEM and XPS results show that the interlayer is responsible for the degraded in-plane orientation, while the various point defects in non-equilibrium sputtering results in those visible emission. Those results demonstrate that increasing sputtering power greatly deteriorate quality of ZnO on 6H–SiC by interlayer and amount of point defects, while exorbitant sputtering power can recover these properties by increasing adatom mobility to some degree.