| AVS 57th International Symposium & Exhibition | |
| Energy Frontiers Topical Conference | Tuesday Sessions |
| Session EN-TuM |
| Session: | Flexible Solar Cells |
| Presenter: | E. Ritz, University of Illinois at Urbana-Champaign |
| Authors: | E. Ritz, University of Illinois at Urbana-Champaign T. Dockstader, Kurt J. Lesker Company L. Meng, University of Illinois at Urbana-Champaign M.J. Neumann, University of Illinois at Urbana-Champaign D.N. Ruzic, University of Illinois at Urbana-Champaign |
| Correspondent: | Click to Email |
The future of electronic devices such as touchscreen phones and large flat panel displays is bright, with their usage only becoming more prevalent in our daily lives. Such devices are dependent on transparent conducting oxides (TCOs) and their continued growth necessitates a manufacturing process that is able to deposit an inexpensive coating with high transparency and high conductivity. Operating using a dual unbalanced DC magnetron system with a secondary RF antenna running at 13.56MHz, a process has been developed that can deposit TCO films such as Indium Tin Oxide (ITO) and Aluminum-doped Zinc Oxide (AZO) without significantly heating the substrate while maintaining high transmission and electrical properties. The system utilizes two 75mm-diameter circular magnetrons with a 2-loop immersed inductive RF antenna between them in order to provide increased ionization. By adjusting RF power from 0W to 300W, ionization fraction can be increased from 20% to over 80% for unbalanced configuration as measured by a gridded energy analyzer. In addition, plasma density is increased with RF enhancement from 1010 cm-3 to 1011 cm-3. This RF enhancement allows for substrate temperatures to remain below 100oC while still achieving film resistivity on the order of 10-3-10-4 Ohm-cm (measured by four-point probe method) and transparency of greater than 90% in the visible wavelengths (measured by spectrophotometery.) Low-temperature deposition expands the possibilities for substrate choice to include plastics, such as polyethylene terephthalate (PET), resulting in flexible TCO films. Adjusting process gas oxygen content (from 0-5%) and RF power allows for a means to tune the film properties to the desired transparency and conductivity. Experiments performed using ITO and 2%-doped AZO with glass and PET substrates. Plasma monitoring accomplished through use of Langmuir probe and optical emission spectroscopy. Additional film quality analysis by means of x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS).