Optimization of Al-doped zinc oxide grown on sapphire using dual-plasma-enhanced metal organic chemical vapor deposition for InGaN/GaN light-emitting diodes

We prpose Al-doped zinc oxide (AZO) grown on sapphire substrate using dual-plasma-enhanced metal-organic chemical vapor deposition (DPEMOCVD). The crystalline quality, optical properties, and electrical characteristics of AZO depend on the deposition temperature. The AZO thin film grown at 185 ^oC shows the highest intensity of (002) preferent orientation for X-ray diffraction (XRD) pattern, highest transmittance of 89 %, highest photoluminence (PL) intensity and lowest full-width at half-maximum (FWHM), and highest carrier concentration and mobility of 3.66 ×10²¹ cm^-3 and 10.08 V/cms, which results a very low resistivity of 1.86 ×10^-4 Ωcm. The PL peak shows a blue-shift for AZO grown at 185 ^oC as compared with ZnO bexause of the Burstein-Moss (BM) effect. In addition, the experimental results represent that the optimized Al content for Al-doped ZnO is 2.88 at % under the deposition temperature of 185 ^oC. Finally, the AZO was deposited on InGaN/GaN light-emitting deodes (LEDs) as transparent conductive layer (TCL). InGaN/GaN LEDs using DPEMOCVD-deposited AZO TCL show a lowest forward resist and highest light output intensity as compared to the those without and with TCL composed of commercial indium-tin-oxide (ITO).