Direct evidence of the dependence of surface state density on the size of SnO 2 nanoparticles observed by scanning tunnelling spectroscopy

• Published in: Surface science Vol. 550; no. 1; pp. 21 - 25
• Main Authors: Maffeı̈s, T.G.G., Owen, G.T., Malagù, C., Martinelli, G., Kennedy, M.K., Kruis, F.E., Wilks, S.P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2004
• Subjects: Computer simulations; Polycrystalline surfaces; Scanning tunneling microscopy; Scanning tunneling spectroscopies; Surface electronic phenomena (work function, surface potential, surface states, etc.); Tin oxides; Tin oxides; Surface electronic phenomena (work function, surface potential, surface states, etc.); Scanning tunneling microscopy; Scanning tunneling spectroscopies; Computer simulations; Polycrystalline surfaces
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2003.11.041

In this work, we report a scanning tunnelling spectroscopy (STS) study of 30 and 10 nm tin dioxide nanoparticles. The STS spectra give a surface band gap of 2.5 eV for both samples and show that the density of surface states in the band gap is around 6 times higher for the 30 nm particles than for the 10 nm particles. This provides direct experimental evidence for our theoretical model, which predicts a decrease in the surface state density as the particle size decreases, and partly accounts for the improved sensitivity of gas sensing devices fabricated with nanoparticles.