SGER: Flexible Thin Film Transistors Using Low Temperature Chemical Bath Deposited Inorganic Semiconductors

Oregon State University, Corvallis OR

Investigators

Abstract

The success of silicon technology over the last few decades has had an enormous impact on our everyday life. Inexpensive and flexible electronic devices will clearly add a new dimension to this continuing revolution. In the last few years, researchers have been taking several routes to realize this dream. Organic semiconductors with their inherent advantage of flexibility have been a popular choice in the pursuit of flexible electronics. However, the low carrier mobility in organic semiconductors is a main obstacle to this approach. On the other hand, it is well known that most inorganic semiconductors have higher carrier mobilities. Herein, we propose a program of research that exploits a novel hybrid approach of using flexible (polymeric) substrates with thin film, high mobility inorganic materials for the active devices. We propose to develop a completely low temperature (< 200 o C) process compatible with the low melting temperatures of polymeric substrates. The thin film inorganic materials will be deposited by low temperature chemical bath deposition (CBD). Several novel device designs based on both MOSFETs and MESFETs that can be realized in an all-low temperature process are proposed. This work will build on our expertise of the successful fabrication of CdS thin film transistor (TFTs) on Si substrates, which show very promising electrical performance. The main research goals are as follows: o Fabricate flexible MOSFET using Al2O3 / Ta2O5 as gate insulator; o Fabricate flexible Schottky gate MESFETs; o Integrate microcontact printing with CBD for device fabrication; o Develop a low cost transistor lab for educational purposes. The research in this proposal will be tightly integrated with a significant educational component. The PI proposes to involve undergraduate and high school students in this research program. Our proposed device fabrication techniques using CBD and soft-lithography can be easily set up even in a non-clean room high school chemistry laboratory. This would motivate high school students towards advanced research as proposed here. The current research program will be integrated into the outreach programs which are currently in place at Oregon State University: (1) Summer Experience in Science and Engineering for Youth (SESEY), and (2) Saturday Academy and Apprenticeships in Science and Engineering (ASE) Program. Each of these programs has a somewhat different focus, but share several common underlying themes: exposure of high school students to careers in science and engineering through research experiences. The PI strongly encourages minorities, women and members of under-represented groups to participate. The PI also proposes to maintain an up-to-date status of the accomplishments of the project on the world-wide-web for the benefit of anyone interested in this field.