Defect etching is a fast and simple technique for the revelation of defects in single-crystalline materials. We propose here three different chemistries that allow accurate monitoring of the density of threading dislocations in germanium. This work especially focuses on solutions that have low etch rates and high selectivity in order to work on thin layers. Moreover, solutions that do not contain any carcinogenic Cr-VI nor HF acid are proposed in order to reduce the impact on environment and the risks for the user. A comparison of the etch rate and the selectivity toward defects is given as a function of the composition of the etching solutions (components and concentrations). A complete procedure for the proper determination of threading dislocation densities is also presented. (C) 2008 The Electrochemical Society.