HOW CAN SENSITIVE AND SELECTIVE SEMICONDUCTOR GAS SENSORS BE MADE

In this paper the theoretical and practical background of the realization of highly sensitive and selective semiconductor gas sensors is discussed. This discussion is based on the literature and some earlier published experimental results. The most important items are the quality of the semiconductor surface, the role of additives (catalytically active materials), the size of crystals or the layer thickness compared to the Debye length of the semiconductor, the quality of the interface between semiconductor crystals and the interface between the semiconductor and the grain of doping material (potential barriers). All of the listed factors depend on the technology; some of them depend on the temperature, as well as the characteristics of the realized sensor or sensor system.