Nanoparticle characterization based on STM and STS

In this review, we describe recent progress made in the study of nanoparticles characterized by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Basic principles of STM measurements and single-electron tunneling phenomena through a single NP are summarized. We highlight the results of electrical and photonic properties on NPs studied by STM and STS. Because nanoparticles are single-digit nanometre in diameter, a single-electron transport on individual nanoparticles such as Coulomb blockade and resonant tunneling through discrete energy levels are investigated. Photon-emission from NPs is also introduced based on STM measurements. Novel single-nanoparticle functions such as stochastic blinking and one-write erasing behaviours are presented. This review provides an overview of nanoparticle characterization methods based on STM and STS that include the detailed understanding of the electrical and photonics properties of nanoparticles.