Carrier Transport Mechanism of Pt Contacts to Atomic Layer Deposited ZnO on Glass Substrates

Abstract

We grew ZnO films at different temperatures on glass substrates using thermal atomic layer deposition and investigated the current conduction mechanism of Pt/ZnO junctions. For ZnO samples grown at 46 and 96°C, the current flow through the ZnO layer was not possible at low temperatures such as 298 and 320 K because the ZnO layer under Schottky contacts were wholly depleted. However, the current conduction was observed with increasing the temperature, which was found to be dominated by the Schottky emission at 360 and 380 K and the Poole–Frenkel emission at 380 and 400 K. For ZnO sample grown at 141°C, the strong tunneling current could occur because very thin depletion region was formed because of the high carrier concentration of ZnO layer. The observed difference in the current conduction can provide a guidance how growth temperature of ZnO should be controlled to design the low-temperature grown ZnO based devices built on glass substrates.

Fig. 1 Current density–voltage (J–V) curves measured at 298 K. The inset in (a) shows the schematic diagram of prepared Pt/ZnO/Al devices.