ABSTRACT
Zinc oxide (ZnO) and its alloys are semiconductors that are used for applications such as transparent contacts for photovoltaics and LEDs, sensors, phosphors, and potentially lasers. Recently, highly conducting ZnO has been attractive because of advantages of cost and toxicity compared with indium tin oxide (ITO) for the light-emitting contact layer on GaNbased LED structures and as a contact layer for photovoltaics. While far behind in development in relation to GaN, ZnO also has potential for transistors and LEDs. ZnO has shown signi‹cant potential as a transparent transistor for displays and made tremendous progress over the last few years for low-cost high-speed transistors. ZnO visible and UV LEDs have also been demonstrated but remain elusive with respect to viable devices. To realize these applications high-quality materials are reproducibly needed with good uniformity of composition, thickness, structure, and doping levels. Metalorganic chemical vapor deposition (MOCVD) is an excellent technology for not only developing such materials but also meeting these requirements-it offers signi‹cant ²exibility and large scalability.
