The influence of iodine on the electrical properties of lead phthalocyanine (PbPC) interdigital planar gas sensors

The electrical behaviour of AuPbPcAu planar gas sensors is studied as a function of exposure to I₂–air mixture. The changes in the I–U characteristics of PbPc thin films on exposure to iodine and after subsequent annealing in vacuum at various temperatures are investigated. It is found that iodine generates acceptor levels within the PbPc energy band gap. The dark current in the devices is studied as a function of temperature and film thickness at a constant bias voltage. The effects of iodine exposure on the film surface and bulk conductivity are identified. The response time and operating conditions for PbPc thin film iodine gas sensors are also reported.