Novel Dielectrics for Transparent Electronics

Oregon State University, Corvallis OR

Investigators

Abstract

Technical. This project aims to improve fundamental understanding of the composition, structure, interface, and electrical properties of thin dielectric films used as gate dielectrics for amorphous oxide semiconductor (AOS) channel transparent thin film transistors (TTFTs). The approach involves synthesis of novel multi-constituent and stacked (laminate) high dielectric constant films on AOS substrates (including In2-xGaxO3, InGaZnO, ZnSnO, ZnInO, ZnO, etc.) via conformal atomic layer deposition (ALD) and low temperature mist vapor deposition (MVD). Materials properties as a function of synthesis method and adjacent AOS material will be inves-tigated using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Simple capacitor test structures and complete TTFT devices will be fabricated. Electrical measurements made on these structures will be used to assess the impact of materials properties on dielectric constant, breakdown strength, dielectric trap density, interface trap density, stability, and electron mobility in the channel. Strong fundamental understand-ing of the Si/SiO2 system (complementary metal/oxide/semiconductor (CMOS) devices) and the a-Si/Si3N4 system (TFT devices) has played a large role in allowing these materials to dominate microelectronics and liquid crystal display applications. A similar understanding of novel dielectrics and their interface with new channel materials will help AOS electronics to approach com-mercialization. Non-Technical. The project addresses fundamental research issues in a topical area of electronic/photonic materials science having technological relevance. Basic understanding gained is expected to lead to improved device performance, and to allow design of new electronic and photonic components. Potential applications include windshield navigational displays and possibility of low cost, high performance transparent alternatives to a-Si TFTs for the display industry. The project will provide opportunities for both graduate and undergraduate students to gain hands-on experience with state-of-the-art thin film synthesis techniques and a broad range of so-phisticated fabrication and analytical characterization techniques while working in a new and exciting field. Results from the proposed study will be disseminated widely in journals and conferences as well as be incorporated into undergraduate and graduate courses taught by the PI. The PI and students involved will participate in two existing high school outreach programs in place at Oregon State University, giving young students early exposure to leading edge research through presentations and hands-on experience. Students will experience broad exposure to multiple disciplines including materials synthesis, analytical characterization, and electrical characterization of materials and devices. Through PI coordination, opportunities will also be available for under-graduate internships in industry.