P-Type ZnO as Multifunctional Material for Optoelectronic Devices

ZnO is one of the most important members of transparent conductive oxide (TCO) materials. ZnO forms a technologically important class of material exhibiting exceptional UV attenuation characteristics blocking 95% of all UV radiation.Since the bandgap of ZnO is well above the visible region prepared film are electrically conductive which is leading to application for transparent p-n junction devices. ZnO naturally shows n-type conductivity due to a large number of native defects such as oxygen vacancies and zinc interstitials which leads to difficulty in achieving p- type ZnO thin films. The difficulty in the formation of p-type ZnO material is due to its self compensation effect deep accepter level and low solubility of accepter dopants. Generally realization of ZnO thin film p-type conductivity may be possible by substituting group-I elements (Li Na K and Ag) for Zn sites or group-V elements (N P As Sb) for O sites or substituting group-III and V elements simultaneously for Zn and O sites respectively.