Capacitance enhancement in the accumulation region of C-V characteristics in metal-insulator-semiconductor capacitors consisting of pentacene and poly(4-vinylphenol)

We report a peculiar enhancement in the accumulation capacitance Cacc in the capacitance-voltage (C-V) characteristics of metal-insulator-semiconductor capacitors consisting of poly(4-vinylphenol) (PVP) and pentacene. Cacc at low frequency C-V was five times larger than the PVP dielectric capacitance CPVP. Cacc decreased as the frequency was increased and returned to the level of CPVP at 1 MHz. The origin of the capacitance enhancement appears to be associated with water molecules adsorbed into the PVP dielectric film when considering the correlation with the concentration of PVP polymer in which OH phenol is known to absorb water molecules.