Thin Au/Ge Schottky diodes for detection of chemical reaction induced electron excitation

Ultra-thin film Au/n-Ge Schottky diodes were used to detect electrons excited by chemisorption of atomic oxygen and atomic hydrogen. The absorption generated a chemicurrent in the diode as ballistic electrons excited by the reaction energy transfer traversed the Schottky barrier. The large-area metal-semiconductor contacts were manufactured under cleanroom conditions by evaporating Au on Ge(0 0 1). By annealing at temperatures between 370 and 400 K under ultrahigh vacuum, the sensitivity to reactive gases may be completely recovered even for samples which were stored under air atmosphere for 1 week or exposed to de-ionized water. The recovery process is explained by desorption of adsorbates and thermal decomposition of oxidized gold layers at the surface. (C) 2002 Elsevier Science B.V. All rights reserved.