Yu Xia Fudan University - Shanghai, China; 2003 B.S. Materials Science Rochester Institute of Technology; 2005 M.S. Materials Science Email: xiaxx023@umn.edu

Organic semiconductors are a promising area of research nowadays, due to their potential to be made into flexible devices with simpler processing and lower cost. It has been widely accepted that the electrical properties of semiconductor transistor devices are strongly dependent on the first few monolayers' lattice structure (or molecular stacking) of those polymers or macromolecules. Thanks to the lack of defects and grain boundaries, a single crystal transistor (SCFET) is the best device to study this relationship. In the research right now, I will focus on materials from the acene family: pentacene, tetracene and rubrene. Single crystals have been made using the LPPVT process. High resolution wide angle x-ray diffraction (HWXRD) and grazing incidence x-ray diffraction (GIXD) have been used to study and compare the surface with the bulk lattice structure of those crystals. A vacuum gap SCFET is fabricated to minimize the contact effects (surface traps, etc.) of the crystal-dielectric interface. The electrical properties of these crystals will be studied using such a device. Furthermore, the temperature of the environment will influence the lattice vibration and defect concentration, and the pressure around the crystal will squeeze the lattice constant to a certain level. The influence of these factors to the corresponding electrical properties will also be studied theoretically and experimentally.