Electrical Characterization and Ammonia Gas Response of a p‐Si/n‐poly[benzimidazobenzophenanthroline] Thin‐Film Junction Diode

Abstract

The electrical characterization and ammonia vapor (NH3) response of a p‐Si/n‐poly[benzimidazobenzophenanthroline] (n‐BBL) thin‐film junction diode are reported. The presence of a depletion layer at the n‐BBL/p‐Si interface is verified via capacitance–voltage measurements, and the built‐in potential is ≈1.8 V. Using the standard diode equation for data analysis, the turn‐on voltage, rectification ratio, and ideality parameter are found to be 2 V, 16, and 6, respectively. The diode is also tested in the presence of NH3 vapor where it retained its asymmetric J–V behavior with increased currents and an insignificant change in device parameters. NH3 is believed to interact with the adsorbed O2− species on the n‐BBL surface liberating electrons that enhance the diode current. The response time, recovery time, and sensitivity of the diode are 65 s, 121 s, and 52%, respectively. The removal of the gas restores the diode characteristics to their near original shape making it reusable. The diode is also electrically characterized as a function of temperature and is found to retain its rectifying behavior down to 150 K. The rectifying and gas‐sensing features make the diode multifunctional, which expands the range of applications of this ladder‐type conducting polymer.