Local probing of thermal properties at submicron depths with megahertz photothermal vibrations

Abstract

We demonstrate the imaging of buried features in a microstructure-a tiny hole in an aluminum thin film covered by a chromium layer-with nanometer lateral resolution using a transient temperature distribution restricted to within ϳ0.5 m of the sample surface. This is achieved by mapping photothermally induced megahertz surface vibrations in an atomic force microscope. Local thermal probing with megahertz-frequency thermal waves is thus shown to be a viable method for imaging subsurface thermal features at submicron depths.

Optical and Optoacoustic Inspection of Niobium Trisulfide Whiskers

“…Noncontact, noninvasive, and nondestructive microscopic or nanoscopic analysis of optical and mechanical properties includes techniques such as the photothermal method 15,16 and surface plasmon resonance. 17−20 Picosecond ultrasonics, a part of laser ultrasonics based on the ultrashort optical pulse, makes it possible to generate an ultrasonic pulse and detect its propagation in a perfectly nondestructive, noncontact, and noninvasive method.…”

Multi-pulse modulation method in photothermal atomic force microscopy for variable frequency modulation of incident light

“…For such purposes, some photothermal spectroscopic methods like a photoacoustic method 5) and a photothermal divergence method 6) were performed. Especially for the local photothermal measurements, in addition, atomic force microscopy (AFM) has been utilized in infrared spectroscopy, 7,8) local probing of photothermally induced megahertz surface vibrations, 9) and direct measurements of thermal expansion by photothermal AFM (PT-AFM) using dual sampling method. [10][11][12][13][14] Furthermore, the principle of micro-drivers based on photo-thermal expansion was examined by AFM, 15) where high sensitivity for height change detection in AFM was utilized.…”

Photothermal Spectroscopic Measurements by Dual Sampling Method in Intermittent-Contact-Mode Atomic Force Microscopy

“…One typical method of PT measurement by AFM is that the periodical thermal expansion at the sample surface excited by a modulated external light is detected by a lock-in technique. Up to now, several attempts on PT measurements by AFM in the contact-mode have been reported, [3][4][5][6] although in these attempts, the optical beam deflection method was used and the influence of stray light on a PT signal was not excluded. In this study, we aimed to realize PT measurements by AFM free from stray light, and therefore, we adopted a piezoresistive cantilever.…”