The temperature dependence of current–voltage characteristics of the Au/Polypyrrole/p-Si/Al heterojunctions

The current–voltage (I–V) characteristics of Au/Polypyrrole/p-Si/Al contacts have been measured at temperatures ranging from 70 to 280 K. The I–V characteristics of the device have rectifying behaviour with a potential formed at the interface. The high values of the ideality factor n depending on the sample temperature may be ascribed to a decrease of the exponentially increasing rate in current due to space-charge injection into the PPy thin film at higher forward bias voltage. The experimental reverse bias I–V characteristics of the device followed the Schottky-like conduction model or Poole–Frenkel effect formulae. A linear temperature dependence of the barrier height Φ_b from the reverse bias I–V characteristics was observed, and the Φ_bo value decreased with lowering temperature, ranging from 0.69 eV at 280 K to 0.22 eV at 70 K.