The STM instrument used in this work was constructed with support from the National Science Foundation under Grant DMR-0960211. B.N.T. and G.V.N. gratefully acknowledge support from the Center for Sustainable Materials Chemistry through the NSF CCI Grant CHE-1102637. D.A.K., J.M.M., and C.F.G. acknowledge support from NSF Grant CHE- 1454036. A.M.G acknowledges the Burroughs Wellcome Fund (Award Number 1007294.01) for financial support. O.E. acknowledges support from the Swedish Research Council and STANDUPP. J.R. acknowledges support from the Swedish Research Council and the Göran Gustafsson’s Foundation. V.K. acknowledges support from the EU’s seventh Framework Programme SNAPSUN, the Swedish National Infrastructure for Computing (SNIC), and eSSENCE.
The Journal of Physical Chemistry Letters
Scanning tunneling microscopy, Nanosilicon, Nanocrystals, Electronic structure
The photophysical properties of silicon semiconductor nanocrystals (SiNCs) are extremely sensitive to the presence of surface chemical defects, many of which are easily produced by oxidation under ambient conditions. The diversity of chemical structures of such defects and the lack of tools capable of probing individual defects continue to impede understanding of the roles of these defects in SiNC photophysics. We use scanning tunneling spectroscopy to study the impact of surface defects on the electronic structures of hydrogen-passivated SiNCs supported on the Au(111) surface. Spatial maps of the local electronic density of states (LDOS) produced by our measurements allowed us to identify locally enhanced defect-induced states as well as quantum-confined states delocalized throughout the SiNC volume. We use theoretical calculations to show that the LDOS spectra associated with the observed defects are attributable to Si–O–Si bridged oxygen or Si–OH surface defects.
Kislitsyn, D. A.; Kocevski, V.; Mills, J. M.; Chiu, S.; Gervasi, C. F.; Taber, B. N.; Rosenfield, A. E.; Eriksson, O.; Rusz, J.; Goforth, A. M.; Nazin, G. V. Mapping of Defects in Individual Silicon Nanocrystals Using Real-Space Spectroscopy. J. Phys. Chem. Lett. 2016, 7 (6), 1047–1054.