Variation of bandgap with oxygen ambient pressure in MgxZn1−xO thin films grown by pulsed laser deposition

Thin films of MgxZn1−xO were grown by pulsed laser deposition technique at various oxygen background pressures in the range of 10−2–10−5 Torr on single crystal (0001) alumina substrates. The films were found to be c-axis oriented with a high crystalline quality having FWHM of rocking curve of about 0.16°. The bandgap of MgxZn1−xO thin films was found to increase from 3.45 to 3.78 eV with decrease of oxygen pressure from 10−2 to 10−5 Torr during the deposition. This has been attributed to the increase in the Mg concentration in the films on decreasing the O2 pressure.