S. Nyembe, T. Ntho, N. Moloto, L. Sikhwivhilu
Keywords: carbon monoxide, indium phosphide, TPD, DRIFTS, gas sensor
Summary:Temperture Programmed Desorption (TPD) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) are crucial spectroscopic methods used to determine thermodynamic and kinetic parameters of desorption processes . Sorption of gases from Group III-V semiconducting nanowires is an area that has not been thoughroughly explored. Indium Phosphide (InP) in particular can be used in various applications such as photonics , electronics including micro and nanoelectromechanical systems (MEMS and NEMS). They have relatively tuneable small direct bandgap of 1.34 eV which makes them suitable for use in optoelectronic devices as well . InP nanowires surface has an interesting electron rich active sites that forms part of the gas binding sites making them potential candidates for gas sensing. The sorption of Carbon monoxide (CO) was studied using TPD and DRIFTS. In this study it was discovered that CO binds through chermisoption to InPNWs. The desorption enthalpies of CO was calculated to be 140 kJ/mol. Gas sensing property of InPNWs was investigated by monitoring the change in the nanowire’s electric current when subjected to the analyte gas. The results that were obtained show that InPNWs are potential CO gas sensors at elevated temperatures (200- 250 ̊C) with excelent responce time of 27.19 seconds. References  P.K Dutta, A Ginwalla, B Hogg, B.R Patton, B Chwieroth, J. Phys. Chem. B, 1999, 103, 4412-4422.  A. Husain, J. Hone, H.W.C Postma, X.M.H Huang, T Drake, M. Barbic, A. Scherer and M.L. Roukes, Appl. Phys. Lett., 2003, 83, 1240- 1242.  A.F.I. Morral, C. Colombo, G. Abstreiter, J. Arbiol, J.R. Morante, Applied Physics Letters, 2008, 92, 1-5.