Avalanche solar blind photodetectors with high responsivity based on MgO/MgZnO heterostructures

High responsivity is important for solar blind detection because solar blind signals are generally weak. In this work, we achieved a high responsivity of 48 A/W at 262 nm via Au/MgO/MgZnO/MgO/Au structured photodetectors at a 10 V bias. Wurtzite Mg0.55Zn0.45O films with a band gap of 4.57 eV were grown on c-plane sapphire by pulse laser deposition and MgO films were deposited on MgZnO films as barrier layers to induce ionization impact for avalanche gain. The photodetectors achieved a rejection ratio (R262-nm/R350-nm) of over 103 and a cut-off wavelength of 273 nm. The time-resolved response measurement showed a response time of 453 μs. The devices performed good stability without degeneration of responsivity under repeating illumination. The high performance of the photodetector implied a wide potential for solar blind application.