This work presents the fabrication, characterization and modeling of inverted staggered a-SiGe:H TFTs with planarized gate electrode. Using this structure two different sequences of fabrication are presented, where spin-on glass and silicon nitride are used as passivation layer, respectively. The results show ambipolar and unipolar behavior in the a-SiGe:H TFTs depending on the fabrication sequence. Also, trap density and characteristic energies for the deep localized states in the a-SiGe:H film are obtained. Using these parameters the device modeling is presented. (C) 2014 Elsevier Ltd. All rights reserved.