A study of the effects of atmospheric adsorption on conductivity of thin silicon films upon heating is presented. A phenomenon is observed without illumination of the sample, that is similar to light-induced thermally stimulated current except no exciting light is applied. The effect is greatly reduced if the sample is annealed prior to cooling. A model involving electrostatic effects coupled with desorption is presented to account for this. (c) 2007 Elsevier B.V. All rights reserved.