Effect of aluminum doping on zinc oxide thin films grown by pulsed laser deposition for organic light-emitting devices
Transparent conducting aluminum-doped zinc oxide (AZO) thin films have been deposited on glass substrates by pulsed laser deposition. The structural, electrical and optical properties of these films were investigated as a function of Al-doping amount (0–4 wt.%) in the target. Films were deposited at a substrate temperature of 200°C in 0.67 Pa of oxygen pressure. It was observed that 0.8-wt.% of Al is the optimum doping amount in the target to achieve the minimum film resistivity and the maximum film transmission. For the 300-nm thick AZO film deposited using a ZnO target with an Al content of 0.8 wt.%, the electrical resistivity was 3.7×10−4 Î©-cm and the average transmission in the visible range (400–700 nm) was 90%. The AZO films grown by PLD were used as transparent anodes to fabricate organic light-emitting diodes. The device performance was measured and an external quantum efficiency of 0.3% was measured at a current density of 100 A/m2.