| dc.description.abstract | In this study, we adopt E-Gun evaporation system to deposit Gallium doped Zinc Oxide (GZO). We analyze the optical and electrical properties of GZO thin film and also discuss the contact property on p-GaN. Finally, we compare the electrical and optical characteristics of GZO TCL LEDs with conventional ITO TCL LEDs.
At the Ga content of 6At.%, we obtained the lowest resistivity (ρ) was 2.44×10-4 ohm-cm which was at the same order of ITO thin film (1×10-4 ohm-cm) and the transmittance was the above 90% at visible range which was comparable with ITO thin film. We prepared two as-deposited GZO films on p-GaN and LEDs of different resistivities, 6.31×10-4 ohm-cm (P-1) and 3.56×10-4 ohm-cm (P-2), to study the electrical contact property and compared with ITO film with resistivity of 1.73×10-4 ohm-cm (P-ITO). The specific contact resistances (ρc) of P-1, P-2 and P-ITO were 7.49×10-1 ohm-cm2, 1.48×10-1 ohm-cm2 and 2.61 ×10-2 ohm-cm2, respectively. After the chip process, we characterized the electrical and optical properties of GZO-LEDs and ITO-LEDs at the injection current of 20mA. The forward voltage of GZO LED-1, GZO LED-1 and ITO-LED were 3.89 V, 3.47 V and 3.35 V, respectively. The forward voltage of GZO-LEDs exhibited 0.54V and 0.12V higher than that of ITO-LED. The output powers were 2.02mW, 1.98mW, and 1.7mW for GZO LED-1, GZO LED-2 and ITO LED, respectively. The output powers were enhanced by 19% and 16% for GZO LED-1, GZO LED-2 compared with that of ITO-LED. On the other hand, the external quantum efficiency were 3.63% and 3.55% for GZO LED-1, GZO LED-2 which showed 18.6% and 16% enhancement compared with that of ITO-LED,3.06%. We also did annealing process for GZO films and then did the chip process. However, we found that? ρ and ρc would be deteriorated after annealing process. At 20mA injection current, the forward voltages were higher than those as-deposit and degradations of EQE and output powers were also observed. | en_US |