INTERACTION OF PLANAR POLYMER SCHOTTKY-BARRIER DIODES WITH GASEOUS SUBSTANCES

Conducting polymers appear very attractive as sensor materials either as the gas-sensitive component or as a matrix for easy immobilization of a specific substrate. The planar Schottky barrier diode with poly(3 -octylthiophene), P3OT, as the semiconductor is used as a sensor for t he detection of different gas species. The shifts in the current-volta ge (C-V) characteristics as well as the C-V characteristics of the dio des due to water and ethanol vapour, ammonia gas and nitric oxide gase s are studied. Nitric oxide and ammonia give the largest and most spec ific changes of the C-V characteristics. Nitric oxide has a doping eff ect, which increases the reverse current, while ammonia is the only ga s that causes a negative change in the forward bias current of the I-V curve. The planar configuration of the Schottky barrier diode facilit ates the absorption of gaseous species in the environment, and provide s a simple method for production of gas sensors.