Degradation mechanism of Al-doped ZnO elements

Accelerated life tests of Al-doped and undoped ZnO elements were carried out using a 50-Hz voltage, and the voltages at a current of 1 mA were measured at various temperatures. Measurements of I-V and C-V characteristics and microstructural analyses using scanning electron microscopy and energy dispersive X-ray analysis were performed. This investigation indicates that Al-doping increases the carrier density of ZnO grain, consequently decreasing the height of back-to-back Schottky barriers, resulting in premature degradation of ZnO elements. It is proposed that the degradation characteristics of ZnO elements can be improved by Ag doping and heat treatment