  In this paper, we demonstrate the principle of operation of a
metal-insulator-semiconductor (MIS) capacitor based on undoped organic
semiconductor. In spite of low charge concentration within the semiconductor,
this device exhibits a capacitance variation with respect to applied gate
voltage $V_g$, resembling the capacitance-voltage $C$-$V$ characteristics of a
traditional doped semiconductor based MIS capacitor. A physics based model is
developed to derive charge concentration, surface potential $\psi_s$ and the
capacitance of organic MIS capacitor. The model is validated with TCAD
simulation results and is further verified with experimental results obtained
from fabricated organic MIS capacitor consisting of poly(4-vinylphenol) and
poly(3-hexylthiophene-2,5-diyl) as insulator and semiconductor, respectively.
