PbSe photodetector arrays for IR sensors

Abstract

PbSe Linear arrays have been fabricated to be used as multiple IR gas sensors at room temperature. PbSe layers were obtained by thermal evaporation in vacuum on SiO 2/Si wafers. Samples became photoconductive after a sensitization process that includes thermal treatments in an iodine-enriched atmosphere. Both morphological features and chemical composition of the layers were studied along the different steps of the sensitization process with a Scanning Electron Microscope. Photoelectrical measurements were also carried out. By comparison between microscopic and photoelectrical measurements, some relations between changes in the morphology of the PbSe layers and changes in their photoconductive behavior were established. The dispersion observed in the photoconductive characteristics of the array elements is associated to the appearance of inhomogeneities during the sensitization process. Whereas the presence of iodine in the sensitization process accelerates the recrystallization rate of PbSe, the presence of oxygen could be responsible for the photoconductivity.