Atomic vibration-induced 1/ƒ noise in sensing nanomaterials

Results demonstrating that the temperature dependence of the 1/f noise intensity in a gold nanoparticle-chemosensor and metallic nanowires is the image of the atomic vibration (phonon) spectrum of the metals they were made of are presented. To this purpose, existing noise data for gold nanoparticles (C. Kurdak et al., Appl. Phys. Lett. 86, 073506, 2005 [1]) and silver and copper nanowires (A. Bid, A. Bora and A. K. Raychaudhuri, Phys. Rev. B 72, 113415, 2005 [2]) are compared with the phonon density of states or phonon dispersion curves of gold, silver and copper, respectively, as determined by neutron/(helium atoms) inelastic scattering (HAS) or high resolution electron energy loss spectroscopy (EELS). It is shown that the noise structure in gold nanoparticles is the image of the gold bulk phonon density of states. In silver nanowires, a noise maximum at 220K is in excellent correspondence with the bulk longitudinal phonon density of states of silver. Other weaker noise peaks are correlated with the surface phonons, including Rayleigh modes. In the case of the copper nanowires, the highest noise peak at 260K is correlated with a transversal bulk phonon, while other peaks are in good agreement with the energy of some Rayleigh modes and surface resonances, at different points of symmetry of the copper surface Brillouin zone. These observations strongly support surface and bulk atomic thermal motion as fundamental sources of 1/f noise in nanoparticles and nanowires, with direct consequences on the physics, design and technology of nanosensors and other nanoelectronic devices.