We present recent developments of the sample preparation technique used to obtain the delineation of a two-dimensional junction profile by transmission electron microscopy analysis. The technique is based on the selective chemical etching of doped regions in silicon by a HF:HNO3 chemical mixture. The role of crystallographic defects and the influence of the substrate doping (n or p type) is explained by taking into account the free carriers present at the solid/solution interface during the silicon dissolution process. This information allows us to identify some crucial aspects of the sample preparation method, and two-dimensional junction profiles can also be obtained in the case of samples doped with boron. The high spatial resolution of the technique allows us to resolve several features of the doping profiles which are not detectable with other techniques and to characterize a wide range of electron devices.