Ohmic contacts to p-type doped ZnO

The electrical property and thermal stability of Pt ohmic contacts were studied.The phosphorus p-doped ZnO films were grown on glass substrates by the thermal evaporation. After the ZnO:P film growth, a Pt (100 nm) contact metal layers were deposited sequentially by dc sputtering. The sample annealed at 600 °C showed the best I-V characteristics of all samples. It was found that the samples annealed at 400, 500, 600 °C were ohmic. For 400, 500, 600 °C samples, the current increased visible reached nano-Ampere grade. Contacts annealed at 500 °C showed the largest current conduction. AFM 3D analysis was conducted to examine the surface morphology of the ZnO:P thin films. The surface roughnesses of the ZnO:P thin films were 11.23, 12.53, 16.70 and 19.21 nm for 300, 400, 500, 600 °C, respectively.