Epitaxial growth of rocksalt Zn1−xMgxO on MgO (100) substrate by molecular beam epitaxy

Zn1−xMgxO films with x=0.22-0.87 were grown on MgO (100) substrates by molecular beam epitaxy at 400 and 600 °C respectively. The films containing 85% or less ZnO grow epitaxially and retain entirely the rocksalt (rs) crystal structure. The rs-Zn1−xMgxO epilayers have a tunable bandgap energy of 4.5-6.2 eV. In addition, the rs-Zn1−xMgxO epilayer grown at 600 °C exhibits a lower FWHM value of its (200) rocking curve as compared to its low- temperature counterpart. The lattice constant of rs-ZnO at ambient pressure and temperature is obtained to be 4.2766 Å. The sticking coefficient of Mg atoms on rs-ZMO is approximately four times higher than that of ZnO atoms regardless of the growth temperature in the range of 400-600 °C.