Photothermal Electrical Resonance Spectroscopy of Physisorbed Molecules on a Nanowire Resonator

Abstract

Mid-infrared (IR) photothermal spectroscopy of adsorbed molecules is an ideal technique for molecular recognition in miniature sensors with very small thermal mass. Here, we report on combining the photothermal spectroscopy with electrical resonance of a semiconductor nanowire for enhanced sensitivity, selectivity, and simplified readout. Wide band gap semiconductor bismuth ferrite nanowire, by virtue of its very low thermal mass and abundance of surface states in the band gap, facilitates thermally induced charge carrier trapping in the surface states, which affects its electrical resonance response. Electrical resonance response of the nanowire varies significantly depending on the photothermal spectrum of the adsorbed molecules. We demonstrate highly selective detection of mid-IR photothermal spectral signatures of femtogram level molecules physisorbed on a nanowire by monitoring internal dissipation response at its electrical resonance.

Effect of interface on mid-infrared photothermal response of MoS2 thin film grown by pulsed laser deposition

“…This observation is similar to the photothermal response of 2D thin films of graphene 20 , graphene oxide 39 and 1-D nanowires. 40 As mentioned earlier, the temperature coefficient of resistance, TCR which is commendable for 2D material in comparison to graphene and strongly reduced graphene oxide (s-GO). 19 However, there is a strong substrate dependence of TCR of MoS2 as seen in case of the film grown on silicon.…”

Surface State‐Induced Anomalous Negative Thermal Quenching of Multiferroic BiFeO3 Nanowires

“…Multiferroic wide‐bandgap semiconductors, such as BiFeO 3 (BFO) have attracted intense research interests due to their broad range of potential applications in optoelectronic devices such as ferroelectric diodes, photovoltaic cells, photodetectors and photothermal sensing . In one dimensional (1‐D) BFO nanostructures, because of their high surface‐to‐volume ratio, surface states play a crucial role in their optical and electrical properties . The surface states may serve as traps for carriers and hence affect the recombination and transport of charge carriers .…”

“…The surface states may serve as traps for carriers and hence affect the recombination and transport of charge carriers . At the nanoscale, surface defect states are more dominant and are very sensitive to external stimuli such as photons, electric fields and temperature . Because of the high density of the surface states in the band gap, carriers from these defect states can be excited with minimum energy.…”

“…[7] In one dimensional (1-D) BFO nanostructures, because of their high surface-to-volume ratio, surface states play a crucial role in their optical and electrical properties. [7][8][9][10] The surface states may serve as traps for carriers and hence affect the recombination and transport of charge carriers. [11][12][13] At the nanoscale, surface defect states are more dominant and are very sensitive to external stimuli such as photons, electric fields and temperature.…”

“…[11][12][13] At the nanoscale, surface defect states are more dominant and are very sensitive to external stimuli such as photons, electric fields and temperature. [7,14] Because of the high density of the surface states in the band gap, carriers from these defect states can be excited with minimum energy. Therefore, changes in surface state population/depopulation due to temperature variations can affect its photoluminescence (PL) spectrum and this phenomenon can serve as a basis for temperature sensing at the nanoscale.…”