Author
Francoeur, M., Mengüç, Mustafa Pınar, Vaillon, R.
Publication Date
2010
Publication Place
-
AIP Publishing
Subject
Thermal radiation, Silicon carbide, Electromagnetic states
Type
Periodical
Language
English
Digital
Yes
Manuscript
No
Library
Özyeğin University
Library Asset ID
1089-7550
Record ID
0d5cf526-a886-43af-aebf-4b2ea6715f18
Library Location
Mechanical Engineering
Date
2010
Sample Text
We present a detailed physical analysis of the near-field thermal radiation spectrum emitted by a silicon carbide (SiC) film when another nonemitting SiC layer is brought in close proximity. This is accomplished via the calculation of the local density of electromagnetic states (LDOS) within the gap formed between the two thin films. An analytical expression for the LDOS is derived, showing explicitly that (i) surface phonon polariton (SPhP) coupling between the layers leads to four resonant modes, and (ii) near-field thermal radiation emission is enhanced due to the presence of the nonemitting film. We study the impact of the interfilm separation gap, the distance where the fields are calculated, and the thickness of the nonemitting layer on the spectral distribution of the LDOS. Results show that for an interfilm gap of 10 nm, the near-field spectrum emitted around the SPhP resonance can increase more than an order of magnitude as compared to a single emitting thin layer. Interfilm SPhP coupling also induces a loss of spectral coherence of resonance, mostly affecting the low frequency modes. The effect of the nonemitting film can be observed on LDOS profiles when the distance where the fields are calculated is close to the interfilm gap. As the LDOS is calculated closer to the emitter, the near-field spectrum is dominated by SPhPs with small penetration depths that do not couple with the modes associated with the nonemitting film, such that thermal emission is similar to what is observed for a single emitting layer. Spectral distribution of LDOS is also significantly modified by varying the thickness of the nonemitting film relative to the thickness of the emitting layer, due to an increasing mismatch between the cross-coupled SPhP modes. The results presented here show clearly that the resonant modes of thermal emission by a polar crystal can be enhanced and tuned, between the transverse and longitudinal optical phonon frequencies, by simply varying the structure of the system. This analysis provides the physical grounds to tune near-field thermal radiation emission via multilayered structures, which can find application in nanoscale-gap thermophotovoltaic power generation.
DOI
10.1063/1.3294606
Cilt
107
