Fabrication of MgZnO films by molecular precursor method and their application to UV‐transparent electrodes

Abstract

MgZnO thin films were fabricated by the molecular precursor method (MPM) for the realization of cost‐effective near‐ultraviolet (UV) transparent electrodes for GaN‐based UV light‐emitting diodes (LEDs). The fabrication by MPM requires a common solution. It was clarified that ammonia aqueous is a common solvent for Mg, Zn and Ga precursors. MgZnO thin film was successfully fabricated on a quartz glass substrate using MgZnO precursor solution. The solid phase composition of Mg in the film is 40‐50% of its molar fraction in the liquid phase. The X‐ray diffraction patterns indicate the films have a hexagonal single phase, the same as in the case of ZnO. Ga doping of the MgZnO films enables their resistivity control. The possibility of applying MgZnO films for UV transparent electrodes on GaN‐based UV LEDs is discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural and Optical Properties of ZnO Thin Films Prepared by Molecular Precursor and Sol–Gel Methods

“…The molecular precursor method (MPM) was employed successfully in the fabrication of copper oxides [31], as well as homogeneous and crack-free titania thin films [32]. Mashiyama and co-workers [33] reported the successful fabrication via MPM of Mg-Zn-O thin films, which exhibited good properties for applications as near-infrared UV-transparent electrodes for GaN-based UV-light-emitting diodes (LEDs). In 2012, Taka and co-authors [34] reported the use of MPM in the fabrication of composite ZnO thin films with dispersed Ag for application in GaInN blue LEDs.…”

Fabrication of c‐axis oriented Ga‐doped MgZnO‐based UV transparent electrodes by molecular precursor method

“…A linearly aligned four-probe measurement system was used to evaluate the resistivity, which was measured at RT. The control of film conductivity was previously investigated using a Ga-nta complex as a Ga precursor, and it was shown that aqueous ammonia can be used as a common solution for Mg, Zn and Ga precursors [1]. The resistivity as a function of the amount of Ga precursor is shown in Fig.…”

“…MgZnO is a potential material for application as UV transparent electrodes. Its absorption edge is located in the range of the UV spectral region [1]. Furthermore, transparent ZnO films [2,3] in the visible spectral region with low resistivity on the order of 10 -4 Ω·cm have been reported [4].…”

“…The metal-released organic compounds remaining are decomposed and evaporated. We have already reported that fabricated Mg 0.1 Zn 0.9 O films are trans-parent at approximately 370 nm in the UV spectral region [1]. However, the resistivities of ZnO and MgZnO films [1] were higher than those of films fabricated under vacuum conditions, partly due to the presence of c-axis orientation [4].…”