This paper presents an overview of the fabrication and the performance of two promising candidates for succession of the conventional MOSFET: the Tunneling FET (TFET) and the vertical impact Ionization MOSFET (I-MOS). These devices offer possibilities to overcome physical limits occurring during the continuous shrinking process like the limitation of the subthreshold swing S to 60 mV/dec at room temperature or rising leakage currents due to tunneling. The performance of these novel devices strongly depends on the shape, level and sharpness of the doping profiles in the active regions. Therefore their fabrication using the vertical transistor concept and epitaxial growth to build the active layers is a very suitable way to achieve a very good device performance. (C) 2008 Elsevier B.V. All rights reserved.