Conductive response of a photo-excited sample in a radio-frequent driven resonance cavity

Abstract

An expression is derived for the perturbative response of a lumped resonance circuit to a sudden change in the circuit parameters. This expression is shown to describe also the photo-induced conductivity of a semiconductor mounted in a single-mode microwave cavity. The power dissipated in the cavity is measured in the two dimensions corresponding to time (after photo-excitation of the sample) and frequency (of the microwave driving source). Analysis of the experimental data for different semiconductor materials demonstrates the general applicability of the presented analytical expression here, by retrieving the time dependence of the sample's photo-induced conductivity.

Photoinduced spontaneous free-carrier generation in semiconducting single-walled carbon nanotubes

“…The details of the solution-phase fp -TRMC experimental setup and discussion are described in Supplementary Figures 3–6 and Supplementary Methods , and the theoretical background of fp -TRMC can be found elsewhere 28 29 39 40 . In brief, in the most general terms, fp- TRMC experiments measure the time evolution of the complex dielectric constant ɛ of the sample after photoexcitation.…”

“…Changes in the real part of the dielectric constant lead to a shift in the resonance frequency, whereas the imaginary part determines microwave power loss in the cavity. Charges photogenerated in the sample (photoconductivity) can contribute to both the real and the imaginary parts of the dielectric constant depending on their mobility and degree of confinement 40 . Conductivity can be expressed in terms of dielectric constant as:…”

“…The details of fp -TRMC experimental setup and its theoretical background have been reported elsewhere 28 29 39 40 and the full accounts of solution-phase fp -TRMC are provided in Supplementary Methods . A schematic instrumental layout is described in Supplementary Figure 3 .…”

Atomic Layer Deposition of ZnO on InP Quantum Dot Films for Charge Separation, Stabilization, and Solar Cell Formation

“…We investigated the photoconductivity upon excitation at 250 nm with a 3 ns laser pulse of the ZnO films with TRMC measurements. Figure d shows the resulting yield‐mobility product which is the number of free charge carriers generated per absorbed photon times the sum of the electron and hole mobility calculated from the photoconductivity per absorbed photon as described elsewhere . We observe that the yield‐mobility product increases with increasing ZnO layer thickness, likely associated to the formation of a more continuous film and availability of an increasing number of charge transport pathways with increasing film thickness.…”

“…TRMC is a contactless spectroscopic technique relating the change in microwave probe power to the sum of electron and hole mobility, ( µ e + µ h ) multiplied by the yield of charge carrier generation, φ( t ), which is a function of time as the photoexcited charges recombine. TRMC measurements were performed in a microwave cavity and photoexcited with a 3 ns laser as described in detail elsewhere …”