Ultraviolet photodetectors with MgZnO nanowall networks grown by molecular beam epitaxy on Si(1 1 1) substrates

Mg0.05Zn0.95O nanowall networks ultraviolet (UV) photodetector was fabricated on Si(1 1 1) by plasma-assisted molecular beam epitaxy. Based on the Mg0.05Zn0.95O nanowall networks, planar geometry photoconductive type metal–semiconductor–metal photodetector was fabricated. At 5 V bias, the peak responsivity of 24.65 A/W was achieved at 352 nm, corresponding to an external quantum efficiency of ∼8490%. Such high external quantum efficiency was attributed to the photoconductive gain, which can be explained by the presence of oxygen-related hole-trap states at the nanowall surface. The response time of 25 ms was determined by the measurements of photocurrent versus modulation frequency.