Zinc oxide (ZnO) grown on sapphire substrate using dual-plasma-enhanced metal organic vapor deposition (DPEMOCVD) and its application

This study reports the use of dual-plasma-enhanced metal organic chemical vapor deposition (DPEMOCVD) in forming low-temperature-grown zinc oxide (ZnO). The proposed method uses a direct voltage (DC)-driven capacitor-coupled electrodes and a radio-frequency (RF) plasma system. The DC plasma system enhances the dissociation of oxygen gas (O2), while the RF plasma system helps maintain the dissociated free radicals in the chamber. The optimum substrate temperature for undoped ZnO grown by DPEMOCVD system is 185 °C, which yields the highest transmittance of 85%, and the lowest resistivity of 6.5 × 10−3 Ω cm. The DPEMOCVD-deposited ZnO was used to the transparent conductive layer (TCL) of InGaN/GaN LED. As compared to the conventional InGaN/GaN light-emitting diode (LED), InGaN/GaN LED with DPEMOCVD-deposited ZnO TCL shows a lower turn-on voltage and higher light output intensity. This indicates that the DPEMOCVD-deposited ZnO can be the TCL for InGaN/GaN LEDs.