We present a methodology for accurate calculation of effective electric field in Ge and GeOI (Germanium-on-Insulator) pMOSFETs, based on the experimental determination of the parameter eta, linking the inversion charge and the effective field. The fabrication procedure of wafers and devices is described. The novel extraction methodology for eta factor has been validated experimentally for both bulk-Ge and fully-depleted (FD) GeOI MOSFETs. A difference in eta of 20% has been found between the two structures. This correction has a significant impact on effective mobility analysis for advanced GeOI-based pMOSFETs. Furthermore, the influence of the temperature on eta parameter has been investigated. The analysis reveals the behavior of the surface roughness limited mobility, which appears to be independent on T and to vary as a function of E-eff(-1) for holes in Ge. An appropriate Coulomb limited mobility modelling is finally proposed, providing relevant information on the interface trap charge in undoped GeOI pMOSFET devices. (C) 2011 Elsevier Ltd. All rights reserved.