Nanoscale mechanical contacts mapped by ultrashort time-scale electron transport.
Mechanical contacts are crucial to systems in engineering, electronics and biology. The microscopic nature of the contacting surfaces determines how they mesh on the nanoscale. There is thus much interest in methods that can map the actual area of two surfaces in contact--the real contact area--during the loading or unloading phases. We address this problem using an ultrafast optical technique to generate non-equilibrium electrons that diffuse across a nanoscale mechanical contact between two thin gold films deposited on sapphire. We image this process in the contact and near-contact regions to micron resolution in situ using transient optical reflectivity changes on femtosecond time scales. By use of a model of the ultrashort-time electron dynamics, we account for an up to ~40% drop in the transient optical reflectivity change on contact. We thereby show how the real contact area of a nanoscale contact can be mapped. Applications include the probing of microelectronic mechanical devices.
Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, 060-8628, Japan.
Motonobu
M
Tomoda
Univ. Bordeaux, CNRS, I2M, UMR 5295, F-33405 Talence, France.
Thomas
T
Dehoux
Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, 060-8628, Japan.
Yohei
Y
Iwasaki
Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, 060-8628, Japan.
Osamu
O
Matsuda
LAUM, UMR CNRS 6613, Université du Maine, LUNAM Université, Av. O. Messiaen, 72085 Le Mans, France.
Vitalyi E
VE
Gusev
Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, 060-8628, Japan.
Oliver B
OB
Wright