Square and collinear four probe array and Hall measurements on metal oxide thin film gas sensors

Gas detection by means of metal oxide semiconductor sensors is ascribed to the change of resistance due to the modulation of the intergrain potential barrier (grain contribution) and of the metal semiconductor barrier at the contacts (contact contribution). We present a method for measuring the contribution of the contact and the grain resistance separately during exposure to CO and CH, by employing the square and collinear four probe array (David S. Perloff, Four-point sheet resistance correction factors fot thin rectangular samples, Solid State Electron. 20 (1977) 681-687). The electronic properties are investigated by means of Hall effect measurements according to grain boundary scattering mechanism. (C) 1998 Elsevier Science S.A. All rights reserved.