Picosecond ultrasonics study of the modification of interfacial bonding by ion implantation

Abstract

We report on experiments in which picosecond ultrasonic techniques are used to investigate the modification of interfacial bonding that results from ion implantation. The bonding is studied through measurements of the acoustic reflection coefficient at the interface. This method is nondestructive and can be used to create a map of the variation of the bonding over the area of the interface.

Thermal boundary conductance of transition metals on diamond

“…A FIB system requires a calibration in the same way as a pro lometer but has the advantage to give a good insight of the microstructure of the layer-for example, its homogeneity and ne surface roughness, and can be used at any point in the lifetime of the sample, including after a heat treatment that changes the layer chemical composition and thus its thickness. Another good method would be to use acoustic echos from TDTR signal (Stoner and Maris 1993;Thompsen et al, 1986), but it has two drawbacks that make an independent measurement useful in our view: (a) if the metallic layer is strongly textured, which is often the case, the speed of sound in it will take the value characteristic for the prominent crystallographic direction and hence may necessitate an additional texture analysis and (b) if the adhesion to the substrate is very strong and the change of acoustic impedance is low, acoustic echos are very dif cult to detect due to high damping even of the rst re ection at the metal/ diamond interface (Tas et al, 1998). To measure thicknesses, FIB cross-sections in the sample were made and the resulting pro le was measured by standard Scanning Electron Microscopy, for example, (Cheng et al, 2009).…”

Imaging of a patterned and buried molecular layer by coherent acoustic phonon spectroscopy

“…The observed damping times for the patterned regions with a base dose multiplier of 100 and 300 are in good agreement with the calculated value of 35 ps for a perfect Au-SiO 2 interface obtained by the acoustic mismatch model. 10 We attribute the slight increase in damping times for higher base-dose multipliers to the FIB patterning, which causes Ga þ ion implantation, amorphisation and damaging of the silicon substrate, and the SiO 2 layer. 27,28 Furthermore, Tas et al showed a distinct influence of ion implantation on the damping times in gold films on He þ doped silicon.…”

“…Coherent acoustic phonon spectroscopy is a versatile tool to image subsurface structures [6][7][8][9] and buried ion implanted surfaces. 10 Several investigations have already been carried out on the elastic properties of ultrathin polymer films with this method. [11][12][13][14][15][16][17][18][19] In our study, we image an embedded and patterned self-assembled organic layer sandwiched between a gold film and a silicon substrate by the damping time of the capping gold layer oscillation.…”

Picosecond Spin Seebeck Effect

“…A description of the experimental setup can be found in the Supplemental Material [32] including Refs. [39][40][41][42][43][44][45][46][47][48].…”