Mg x Zn1– x O/ZnO Quantum Well Photodetectors Fabricated by Radio-Frequency Magnetron Sputtering

Mg x Zn 1-x O/ZnO quantum well (QW) photodetectors were fabricated by a radio-frequency magnetron sputtering system. The QW structure largely reduced the leakage current, from 2.6 × 10 -7 to 1.0 × 10 -9 A, by a factor of 260. The reduced leakage current enhanced the photo-to-dark current ratio from 1.35 × 10 3 to 4.25 × 10 4 , a 32-fold increase for the photodetectors with the QW structure. The 340 nm/560 nm rejection ratio was increased by a magnitude of 5.6 compared to that of photodetectors without QW structure because the electron-hole pairs generated by low-energy photons were confined in the Mg x Zn 1-x O/ZnO QW.