Fabrication of high quality silicon–polyaniline heterojunctions

A high quality silicon–polyaniline heterojunction is produced by spin-coating of soluble polyaniline on silicon substrates. The devices have excellent reproducibility of their electrical characteristics and high rectification ratio. The rectification ratio is 60,000 at ±1.0 V at room temperature, and typical reverse current at −1.0 V is 3 nA. A G/I×G plot is used to analyze the current–voltage characteristics, yielding typical series resistance of 4 kΩ and ideality factor in a range from 1.0 to 2.0. The devices present great potential for use as radiation and/or gas sensors.