AVS 51st International Symposium
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP4
Nanoscale Current Mapping of Indium Zinc Oxide Thin Films Investigated by Conducting Atomic Force Microscopy

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: C.Y. Su, National Science Council, Taiwan
Authors: C.Y. Su, National Science Council, Taiwan
H.C. Pan, National Science Council, Taiwan
M.H. Shiao, National Science Council, Taiwan
C.N. Hsiao, National Science Council, Taiwan
Correspondent: Click to Email
Transparent conducting oxide (TCO) films such as impurity-doped indium oxide systems have been widely applied for opto-electronic devices. Recently, several advantages of ZnO doped indium oxide (IZO) thin film has been reported. Since the photon emissive layer thickness of a device is typically in the range around 100 nm, understanding of the microscopic evidences for improving device performance is required. We have used the technique of conducting atomic force microscopy (CAFM) to investigate the relations between local surface electrical properties and morphologies of IZO thin films treated by different cleaning methods. The conducting regions are attributed to zinc oxide distributed randomly in the average size of 35 nm. Microscopic current mapping indicates ultraviolet-ozone (UV-ozone) treatment is contributed to produce nonconductive region due to generation of stable oxide as reported previously. By applying a tip bias of over -9 V on the nonconducting region, UV-ozone treated sample showed resistance against decomposition while the others failed. This stable oxide acts as a hole transport layer between the photon emissive layer and IZO thin film, which improves stability of devices by decreasing degradation rate of device performance. The surface oxide layer is generally attributed to increasing the work function after UV-ozone treatment, and higher efficiency is achieved as a result of reduction in energy barrier by improving interfacial conditions. Similarly, an additional ultra-thin SiO@sub 2@ layer deposited over IZO thin film would optimize electrical properties for improvement of device performance.