Near-field radiative heat transfer between nanoporous GaN films

Abstract

Photon tunneling effects give rise to surface waves, amplifying radiative heat transfer in the near-field regime. Recent research highlights that introducing nanopores into materials creates additional pathways for heat transfer, leading to a substantial enhancement of near-field radiative heat transfer (NFRHT). Being a direct bandgap semiconductor, GaN offers high thermal conductivity, stable resistance at high temperatures, and holds significant potential for applications in optoelectronic devices. Indeed, the study of NFRHT between nanoporous GaN films is currently lacking, hence physical mechanism on adding nanoporous in GaN films remain to be discussed in the field of NFRHT. In this work, we delve into the NFRHT of nanoporous GaN configuration in terms of gap distance, the thickness of GaN film and vacuum filling ratio. The results demonstrate a 27.2% increase in heat flux at a 10 nm gap when the nanoporous filling ratio is 0.5. Moreover, spectral heat flux exhibits redshift with the increase of vacuum filling ratio. To be more precise, the peak of spectral heat flux moves from ω = 1.31 × 1014 rad/s to ω = 1.23 × 1014 rad/s when the vacuum filling ratio changes from f = 0.1 to f = 0.5, which can be attributed to the excitation of surface phonon polaritons. The introduction of graphene in these configurations can highly enhance the NFRHT, and spectral heat flux exhibits blueshift with the increase of vacuum filling ratio, which can be explained by the excitation of surface plasmon polaritons. These findings offer theoretical insights that can guide the extensive utilization of porous configurations in thermal control, management as well as thermal modulation.