Infrared Imaging of the Nanometer-Thick Accumulation Layer in Organic   Field-Effect Transistors
  We report on infrared (IR) spectro-microscopy of the electronic excitations in nanometer-thick accumulation layers in FET devices based on poly(3-hexylthiophene). IR data allows us to explore the charge injection landscape and uncovers the critical role of the gate insulator in defining relevant length scales. This work demonstrates the unique potential of IR spectroscopy for the investigation of physical phenomena at the nanoscale occurring at the semiconductor-insulator interface in FET devices. 
Z.Q. Li, G.M. Wang, N. Sai, D. Moses, M.C. Martin, M. Di Ventra, A.J.   Heeger, D.N. Basov