Recent Developments of ZnO-Based p-type Transparent Conductive Oxide Thin Films

摘要

Nowadays,high performance p-type transparent conductive oxide (TCO) thin films have gained tremendous intersts,and the fact is that if p-type TCOs with high electrical conductivity and optical transmittance can be fabricated,transparent p-n junctions can be obtained and “invisible electronics” be realized,and hence the use area of TCOs will be highly broadened.A lot of work have been done on non-stoichiometric and doped versions of p-type TCOs in the last few years to improve the optical and electrical properties by various deposition techniques.ZnO-based thin films were thought to be the most promising candidate for p-type TCOs based on the fact that ZnO has advantages over the others,so in this paper the development of ZnO-based p-type TCOs has been discussed.Firstly,the reasons why p-type ZnO-based TCOs are difficult to synthesize were discussed,and then the general ways now used to produce p-type ZnO-based TCOs were summerized,including intrinsic p-type ZnO,doping of groupⅠelements,codoping of Ⅴand Ⅲ elements,doping of group Ⅴ elements,the origin of p-type conductivity and the feasibility of each way,and the state-of-the-art optical and electrical properties were presented.Finally,the specific shortcomings in producing high quality p-type TCOs were discussed.Based on the comparision,it is believed that the doping of group Ⅰelements in ZnO may be the most pronising way in realizing p-type TCO.