Depletion layers, plasmon dispersion, and the effects of temperature in degenerate InSb(100): A study by electron-energy-loss spectroscopy

Size-dependent nonlocal effects in plasmonic semiconductor particles

“…This charge carrier depleted layer stretching a few hundred angstrom into the material has been discussed in earlier papers 12,[64][65][66] . Such a layer would be significant for the optical properties of the InSb particle, and the question of how it would affect the nonlocal effects is still to be answered.…”

“…Another phenomenon relevant for especially binary and ternary semiconductors is optical phonons which may couple to the plasmon if the resonance frequency is in the same region. This has been investigated for InSb 61,62 and GaAs 18,63 , and the mechanism could be included in the dielectric function as an extra term (as is done in [12]). …”

“…This situation would of course be complicated by the relaxation of the charge carriers over time, and assumptions about a quasi-equilibrium would have to be made (and we will not consider this here). Note, that the two expressions for β also can be found in [12]. The equations for the plasma frequency ω p and the damping rate γ, however, are independent of the excitation method and in all cases are given by…”

“…An example is InSb which is characterized by an extremely small band gap (E g ∼ 0.17 eV) and a high charge carrier density at room temperature. This material was used by Hanham et al, as well as in earlier papers on plasmonics [11][12][13] , and in all cases the charge carriers were treated as a plasma. Another example is doped semiconductors where additional charge carriers have been supplied by the donors or acceptors.…”

Two-fluid hydrodynamic model for semiconductors

“…It should also be mentioned that for InSb, in particular, a charge-carrier depleted region known as the space-charge layer may exist close to the surface which would be relevant for the optical properties. This layer has been investigated in several earlier papers [34,[78][79][80], and the question of how it affects features such as the acoustic peak still remains. Finally, the two-fluid model, just as the single-fluid HDM, does not account for Landau damping whereby the energy of the plasmons dissipates into single-particle excitations.…”