NO2 sensor based on InP epitaxial thin layers

n-InP epitaxial thin layers are exposed to concentrations of a diluted oxid izing gas: NO2. in the presence of this gas, the resistance measured parall el to the surface of the InP layer, between ohmic contacts, increases. The magnitude of its variations depends on several parameters: the operating te mperature, the thickness and the doping concentration level of the InP laye r, and the gas concentration. A theoretical model of the action of the gas is proposed, mixing chemisorption equilibrium and surface field effect. The experimental results are in agreement with the theoretical predictions. (C ) 1999 Elsevier Science S.A. All rights reserved.