Reproducible and strong diode-like behaviour is observed for molecular films of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) on n-type Si(111)- 7×7 surfaces studied by scanning tunnelling microscopy (STM) and spectroscopy (STS) at 77 K. The mechanism behind the rectification is likely to be related to the electron distribution at the molecule-silicon interface. We suggest that the adsorption of the molecular layer profoundly modifies the electronic structure of the Si(111)- 7×7 surface.
Hallbäck, A. S. V. M., Poelsema, B., & Zandvliet, H. J. W. (2007). Rectification behaviour of molecular layers on Si(111). Solid state communications, 141(12), 645-648. https://doi.org/10.1016/j.ssc.2007.01.015