III–V Nanowires for Biological Ammonia Concentrations Detection

Ammonia are found both in nature and in human body, and its detection is very important in biology and medicine as well as in environmental monitoring systems. This work is aimed at fabrication and study of precise, technological and relatively cheap ammonia sensors compatible with a liquid medium. Here we use III–V epitaxial nanowires (NWs) as adsorption elements for ammonia sensors fabricated via a simple protocol. The device properties with addition of ammonia to the reference medium (water) are studied in terms of change in sensor impedance spectrum. The potential of electrical impedance spectroscopy for characterisation of interaction between low–dimensional nanostructures and environment is shown. Ammonia sensors based on III–V NWs have been developed, and a physical interpretation of their impedance spectra in the presence of water and ammonia is given. GaP and GaN–based devices exhibit sufficient response to the ammonia presence with the detection limit lower than 2,5ppm.