ZnO-based Ultraviolet Avalanche Optoelectronic Devices

ZnO-based materials have been considered as promising candidate in ultraviolet(UV) optoelectronic devices for their unique properties, such as wide tunablebandgap, large exciton binding energy, low preparation temperature, availability ofhomogeneous single crystal substrate, and strong radiation-resistence, etc. In thisthesis, aiming at ZnO-based avalanche photodetectors and light-emitting devices, asystematic study has been conducted, and the main results obtained are listed below:1. In virtue of the carrier multiplication caused by an impact ionization processoccurred in MgO insulation layer under relatively large electric field, ZnO ultravioletavalanche photodetectors have been fabricated from Au/MgO/ZnO/MgO/Austructures. The avalanche gain and maximum responsivity of the photodetector isabout294and1.7×104A/W at73V, respectively.2. MgZnO-based APDs have been realized in an Au/MgO/MgZnO/MgO/Austructure. The device has a low avalanche threshold voltage of16V and theavalanche gain is587at31V bias.3. By using the hole generated in the avalanche multiplication process,ZnO-based light-emitting devices have been fabricated from Au/MgO/ZnO/MgO/Austructures, and the near-band-edge emission of ZnO has been observed from theLEDs.