Artificial molecules are fabricated on a silicon surface. The constituent atoms are silicon dangling bonds created by selective removal of H atoms from an otherwise fully H atom terminated silicon surface. A 4 Kelvin scanning tunneling microscope is used for the fabrication, imaging and spectroscopic analysis of the molecules. We explore primarily the close coupling regime, where there are no intervening H atoms between dangling bonds. Local density of states maps, varying energy and position, reveal highly complex electronic structure. Assignment of the observed structures to explanations such as particle in a box states found to be adequate for other scanning tunnel microscope fabricated structures, was clearly unsatisfactory. It emerged that - because our atoms are in the band gap - remarkable charged states participate and indeed dominate the observed electronic structures. Beautiful patterns in electron filling as a function of size are identified. Some previous studies considered a subset of the entities considered in this study. In those reports less rigorous spectroscopic analysis was performed. By using more informative methods and by exploring a greater variety of structures it has been possible to eliminate some previous models that had been put forward. Electrostatic perturbation of the artificial molecules is demonstrated and it is recognized that a new form of ultra low power information transfer has been established. This effect is being applied in new architectures for ultra low power classical computation and for quantum computing. Finally, it is stressed again that the constituent atoms, and the molecules, have gap states. Crucially, this allows for surface circuitry that does not connect with bulk states - unless - that connection is desired.

Properties of multiple silicon atom artificial molecules on a silicon surface

253rd National Meeting (2017)

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