By adding electrical read-out, our s-SNOM is modified to enable scanning nearfield photocurrent nanoscopy and nano-spectroscopy. This capability measures lateral photocurrent or photovoltage at higher harmonics of the tip-light modulation, instead of measuring purely the scattered light of a typical s-SNOM.
Photo-electrical response originated from nanoscale features (such as quantum-confined structures, defects and grain boundaries) can be mapped at lateral resolution of ~ 20 nm. Both visible and IR sources are available for this measurement mode.
Such measurements are suitable for characterising a wide range of optoelectronic devices (such as photothermoelectric detectors, photovoltaic light sensors and photo-FETs), especially providing valuable information on device quality and uniformity by assessing nanoscale variations.
This technique measures materials IR absorption at nanoscale. Upon absorbing IR radiation, local thermal expansion of the sample is mechanically detected by the AFM tip. Measurement of point IR absorption spectra and 2D mapping can be achieved in a variety of configurations including contact, resonance-enhanced and tapping modes with the QCL or OPO as sources of monochromatic, tuneable illumination.
This technique is suitable for chemical identification of a sample surface at nanoscale, such as investigating contaminations, mapping mixtures of organic blends, or characterising biochemical functionalisation of advanced materials.