Study On Doping MgZnO Film UV Photodetectors

Ultraviolet is weak in the atmosphere and for its short propagation length,multiplication effect is necessary in ultraviolet photodetector. Schottky junction is agood choice for high performance ultraviolet photodetectors. It works based on thebarrier between the metal and semiconductor as they are connected. So it’s easilyinfluenced by the surface state of the active layer of the device. As an important wideband gap semiconductor, zinc oxide has been investigated in many forms, amongwhich MgZnO alloy is believed to be the most efficient candidate for deepultraviolet photoelectronic device due to its large tunable band gap. MgZnO has beenextensively studied for its optics and electricity properties based on its wideapplications as photodetector. A part of the studies were focused on the nanosizedMgZnO with the purpose of improving the light absorption, therefore another partfocused on the quantum well structures to reduce the internal field in order to increasethe internal efficiency:1. We report on a Schottky ultraviolet photodetector with a MgZnO: Altransparent electrode. By using doping and post annealing, transparent conductiveMgZnO:Al thin films was developed to fit the request for our detection. The deviceis structured vertically in an order of sapphire/MgZnO: Al/as-grown MgZnO/Au.The device shows a good Schottky contacting character. The peak response is located at340nm and cut-off at355nm. The turn-on voltage is2.0V and thebreakdown voltage is40V. The leakage current is less than70pA at a reverse biasof15V.2. The metal-organic chemical vapor deposition method was successfully usedto synthesize pure MgZnO and Ga doping MgZnO. The flow rate of TEGa waschanged to study how the dopant-Ga affect the structure of MgZnO. The MgZnOstructure was verified with x-ray diffraction, which showed typical characteristicsphalerite reflections without any separate dopant-related peaks.. X-ray diffractionalso demonstrate that along with the growth of Ga dopant in number. ZnGa2O4isturned up in the film which made the MgZnO phase split. Scanning electronmicroscopy observations confirmed the existence of homogeneously distributedhexagonal crystal and cubic crystal and a little rhombus crystal.