Effect of iodine pressure in the sensitization treatment on the structural and electrical properties of PbSe films

Influence of iodine vapor pressure during the sensitization process on the morphology, microstructure, and electrical properties of the PbSe films was studied. PbSe films of polycrystalline particles were coated on thermally oxidized silicon substrates by chemical bath deposition using a solution of lead acetate and sodium selenosulfate without or with iodine-doping. As-grown PbSe films were oxidized at 380°C for 30 min and then treated with iodine vapor of different pressures at 380 °C for 5 min. As the iodine vapor pressure was increased above 20 Pa during the iodination process, the PbI2 phase begins to form in the undoped films, while the PbI2O2 and Pb3O4 phases as well as PbI2 are formed in the iodine-doped films. Only iodine-doped films showed photo response. The sheet resistance and the signal to noise ratio increased with the iodine vapor pressure up to the 17.5 Pa iodine pressure. The role of iodine in the sensitization is thought to be helping recrystallization of PbSe grains and the resultant redistribution of oxygen atoms in the effective atomic sites.