Effects of thermal treatment on the MgxZn1 − xO films and fabrication of visible-blind and solar-blind ultraviolet photodetectors

• Single-phase wurtzite/cubic MgxZn1 − xO films were grown by RF magnetron sputtering technique.
• We focus on the red-shift caused by annealing the MgxZn1 − xO films.
• MSM-structured visible-blind and solar-blind UV photodetectors were fabricated.

A series of single-phase MgxZn1 − xO films with different Mg contents were prepared on quartz substrates by RF magnetron sputtering technique using different MgZnO targets, and annealed under the atmospheric environment. The absorption edges of MgxZn1 − xO films can cover the whole near ultraviolet and even the whole solar-blind spectra range, and the solar-blind wurtzite/cubic MgxZn1 − xO films have been realized successfully by the same method. In addition, the absorption edges of annealed films shift to a long wavelength, which is caused by the diffusion of Zn atoms gathering at the surface during the thermal treatment process. Finally, the truly solar-blind metal-semiconductor-metal structured photodetectors based on wurtzite Mg0.445Zn0.555O and cubic Mg0.728Zn0.272O films were fabricated. The corresponding peak responsivities are 17 mA/W at 275 nm and 0.53 mA/W at 250 nm under a 120 V bias, respectively.

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