Single-electron tunneling in a single PbS nanocrystal nucleated on 11-mercaptoundecanoic acid self-assembled monolayer at room temperature

Nanometer-sized PbS particles in the size of about 3 nm produced by exposing a self-assembled monolayer of 11-mercaptoundecanoic acid salts on gold (111) substrate in a H2S atmosphere were studied by scanning tunneling microscopy (STM) and high-resolution transmission electron microscopy at room temperature in air. The stability of thus-obtained PbS nanoparticles makes STM imaging possible and repeatable scans of the semiconductor nanoparticles were performed. The current-voltage (I--V) characteristics of a single PbS nanoparticle exhibited clearly Coulomb blockade and Coulomb staircase. Furthermore, by varying the gap between a STM tip and the PbS nanoparticle, we also verified the dependence of staircase width on the change of the gap in the local I--V characteristics on the same PbS nanoparticle. The phenomena can be well described by a semi-classical double-barrier tunneling model. copyright 2001 American Institute of Physics