High quality Schottky sandwich devices were fabricated on an InP single crystal by solution processing a semiconducting polymer, DNA, as the metal electrodes. We observed that DNA-based on this structure showed an excellent rectifying behavior with a typical ideality factor of 1.26, and that DNA film increased the effective barrier height by influencing the space charge region of InP. Modeling, which includes a transport mechanism, reveals thermionic emission to be the dominant transport mechanisms for the diode (ideality factor n < 1.3). We proposed that DNA could be a semiconductorlike material with a wide optical band energy gap of 3.95 eV from its optical absorbance characteristics. We also evaluated photovoltaic characteristic of the device under an illumination condition. (c) 2008 American Institute of Physics.