In an impressive piece of experimental work, researchers have created transistors utilizing a single phthalocyanine molecule (gate) sitting atop a cleaved InAs surface (drain) and probed by a cryogenic STM tip (source). The data reveals a much larger band gap than can be explained purely electronically. Imaging the phthalocyanine along with its InAs host reveals that the charge state of the phthalocyanine, induced by electron transfer from the tip, causes the phthalocyanine to rotate relative to the InAs lattice. The authors explain that the phthalocyanine is bound to the InAs surface only through van der Waals forces. One might therefore expect similar behavior in molecular scale systems with weak binding.
Ref.: J Martinez-Blanco, et al., “Gating a single-molecule transistor with individual atoms”, Nature Physics 11, 640–644 (2015); reprinted as arXiv:1603.00908.