Investiaations On AZO Thin Films And Its Application To GaN Based LED As Transparent Electrodes

Al-doped ZnO (AZO) films were grown by pulsed laser deposition (PLD) and DC magnetron sputtering. We explored its applications to GaN-based light emitting diodes (LEDs) as transparent electrodes. The main study work focus on the following several aspects:1. AZO thin films were grown by PLD, and the influences of sputtering temperature and oxygen pressure on the properties of the film were studied. The films were used as the transparent electrodes of GaN based LEDs. At a forward current of20mA, it is observed that the chip with a high working voltage of～10V only show an emission in some regions. Further experiments proved that the high working voltage due to the change of conductivity and the formation of20～30nm passivation layer at the AZO/GaN interface.2. AZO films were grown by DC magnetron sputtering. The AZO/ITO composite films were used as the transparent electrodes of GaN-based LEDs. Several different process programs were studied. The process program of depositing AZO/ITO composite films firstly and then etching was determined. To meet the requirements of process program, the films should not be too thick and the lithographic plate without hole.3. We studied the AZO/ITO composite films with different ITO and AZO thickness to the effected on the performance of the chips. The properties of LEDs with500nm AZO/20nm ITO transparent electrodes are as well as LEDs with300nm ITO transparent electrodes. Using AZO/ITO composite films replace300nm ITO, the replacement rate was93%and the usage of indium was saved.