“…This field-effect transistor (FET) design can be considered as a first-generation approach. To explain the emergence of the observed electrical facet effects, density functional theory (DFT) calculations have revealed the presence of an ultrathin surface layer (∼1 nm or less in thickness) with dissimilar band structures for various surface planes, which should lead to different degrees of surface band bending and facilitate or prevent charge transport across a particular crystal face. ,,,− Furthermore, bond length and bond directions, as well as frontier orbital electron energy distribution, within the thin surface layer can show deviations or variations for the highly conductive crystal faces such as the Si (111) and Cu 2 O (111) planes, which should yield changes in the surface band structure. , These DFT results provide a more physical picture of the thin surface layer. Interestingly, the predicted structural deviations in the surface lattice planes may be observable, as seen in the high-resolution transmission electron microscopy (HR-TEM) images of SrTiO 3 crystals with slight atomic position deviations and noticeable peak shifts in the X-ray diffraction (XRD) patterns of polyhedral Cu 2 O crystals. , To gain further insights, the most conductive Si and Ge {111} wafers were found to have the lowest surface trap state population and the shortest carrier lifetime, matching with their best electrical conductivity behavior. , GaAs wafers, however, do not show such surface trap state and carrier lifetime correlation to their conductivity properties …”