Vibrational and electronic heating in nanoscale junctions

Abstract

Understanding and controlling the flow of heat is a major challenge in nanoelectronics. When a junction is driven out of equilibrium by light or the flow of electric charge, the vibrational and electronic degrees of freedom are, in general, no longer described by a single temperature[1-6]. Moreover, characterizing the steady-state vibrational and electronic distributions {\it in situ} is extremely challenging. Here we show that surface-enhanced Raman emission may be used to determine the effective temperatures for both the vibrational modes and the flowing electrons in a biased metallic nanoscale junction decorated with molecules[7]. Molecular vibrations show mode-specific pumping by both optical excitation[8] and dc current[9], with effective temperatures exceeding several hundred Kelvin. AntiStokes electronic Raman emission\cite[10,11] indicates electronic effective temperature also increases to as much as three times its no-current values at bias voltages of a few hundred mV. While the precise effective temperatures are model-dependent, the trends as a function of bias conditions are robust, and allow direct comparisons with theories of nanoscale heating.

28 pages, including 4 main figures and 10 supplemental figures

References in corpus (6)

• Single-Molecule Circuits with Well-Defined Molecular Conductance
• Electromigrated nanoscale gaps for surface-enhanced Raman spectroscopy
• Simultaneous measurements of electronic conduction and Raman response in molecular junctions
• Heat conduction in molecular transport junctions
• Current induced light emission and light induced current in molecular tunneling junctions
• Electronic and optical properties of electromigrated molecular junctions

Cited by in corpus (2)

• Laser-like vibrational instability in rectifying molecular conductors
• Light-induced current in molecular junctions: Local field and non-Markov effects