Light emission induced by tunneling electrons from surface nanostructures observed by novel conductive and transparent probes

Abstract

We have developed an ultrahigh-vacuum low-temperature scanning tunneling microscope (STM) equipped with a near-field optical detection system using novel conductive and optically transparent probes. Tunneling-electron induced photons generated in a nanometer-scale area just under the STM probe can be collected directly into the core of the optical fiber probe within the optical near-field region. Firstly, optical fiber probes coated with indium-tin-oxide thin film are applied to quantitative analysis of p-type GaAs(110) surface, where a decrease of light emission in photon mapping clearly extracts the existence of Zn accepter atoms located at the sub-surface layers. Secondly, in order to enhance the efficiency for inelastic tunneling excitation of a tip-induced plasmon mode, a STM probe coated with an Ag/ITO dual-layer film has been developed and applied to an Ag(111) surface, where photon mapping with a step resolution has been achieved by near-field detection.

Localized Light-Matter Interactions with Optical Antennas

“…In order to confirm the role of the gap plasmon in STM-LE, it is necessary to uncover the origin of the line-to-line photoemission intensity variations seen in previous 2-dimensional STM-LE studies [48][49][50][51][52]. These line-to-line variations are typically associated with changes in the probe as it interacts with the sample; however, there have also been reports of electroluminescent (EL) metal clusters being created and/or destroyed within tunnel junctions in a planar geometry [53][54][55].…”

Simple and efficient scanning tunneling luminescence detection at low-temperature

“…The ability to do polarized measurements without the need to install in situ polarization filters and rotation mounts is a further advantage of the current and other designs [11][12][13][14] over designs that employ an in situ optical fiber to collect the luminescence. 8,15,16 …”

Active nanocharacterization of nanofunctional materials by scanning tunneling microscopy

“…Moreover, STM has the unique capability of locally probing electronic states, which are closely related to novel nanofunctionality. For example, STM with tunneling spectroscopy can be used to perform atomically resolved spectroscopy imaging functions such as energy-resolved local density of states (LDOS) mapping [5], spin-polarized tunneling imaging [6], molecular vibrational spectroscopy by inelastic tunneling [7], and tunneling-induced photon emission mapping [8]. This versatility as an analytical probe makes STM a powerful tool for exploring novel properties and the innovative functions of nanomaterials.…”