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Influence of Oxygen in the Sensing Properties of Cadmium and Germanium Oxynitride

1996; American Chemical Society; Volume: 12; Issue: 6 Linguagem: Inglês

10.1021/la950207j

1520-5827

José J. Benı́tez, M.Á. Centeno, C. Picard, J. Guyader, Y. Laurent, J.A. Odriozola,

Luminescence Properties of Advanced Materials

A novel cadmium and germanium oxynitride (CdGeON) sensor, originally designed for NH3 and SH2 detection, has been studied by in situ Fourier transform diffuse reflectance infrared spectroscopy (DRIFTS), XPS, and UV−vis in order to elucidate the influence of an oxygen-containing environment on the sensor's electrical response. Under oxygen, the conductivity of this sensor is directly related with DRIFTS bands at 810, 780, and 580 cm-1 assigned to oxygenated species bonded to single Ge atoms. These species are reversibly eliminated or restored in the solid framework upon heating in N2 or synthetic air, respectively. XPS and UV−vis spectroscopies have confirmed the oxygen uptake and the increase in the coordination number of Ge atoms upon exposure of the CdGeON sensor to synthetic air. A similar conclusion is presumed for Cd atoms although no conclusive results can be inferred from the UV−vis spectra. From the analysis of the resistance-temperature Arrhenius-type relationships, a model involving the filling of anionic vacancies is proposed to explain such a differenciated behavior under synthetic air.