Enhanced Light Extraction for InGaN/GaN LEDs Using Zn and Mg Driven-In ALD-GZO as Transparent Conducting Layer

To enhance the transmittance in short wavelengths of gallium-doped zinc oxide (GZO) films, we employed Zn and Mg driven-in GZO films prepared by atomic layer deposition (ALD) via the novel method of rapid thermal diffusion. The ultraviolet (UV)-visible spectrum shows a significant blue shift of the absorption band edge and an increasing optical bandgap for the Zn and Mg driven-in GZO films. Through Zn and Mg driven-in GZO as transparent conducting layer onto 400- and 380-nm InGaN/GaN light-emitting diodes (LEDs), the electroluminescence intensity of 400- and 380-nm LEDs with Zn and Mg driven-in GZO films has nearly 1.4 and 2.5 times of magnitude stronger than the conventional LEDs only with GZO films at 20 mA. The 400- and 380-nm LEDs with Zn and Mg driven-in GZO films also reveal a light output power of 7.7 and 1.9 mW at 20 mA as compared with the conventional LEDs only with GZO films of 6.1 and 0.7 mW, respectively. The 400- and 380-nm LEDs also exhibit an enhancement of 27% and 166% in light output power. These results present that Zn and Mg driven-in ALD-GZO films have significant improvement for the light extraction on the shorter wavelengths for the violet and UV LEDs.