Strong light-matter coupling at room temperature in simple geometry GaN microcavities grown on silicon

The reflectance spectra of simple design GaN-based microcavities have been studied in the 5 K–300 K range. The epitaxial structure consists of the silicon substrate and the stack of buffer layers as the back mirror, a GaN active layer, and a 100 Å thick aluminium layer as the top mirror. Active layer thicknesses of $λ∕2$⁠, $λ$⁠, or $3λ∕2$ were investigated. The samples with GaN thicknesses $λ∕2$ and $λ$ display an anticrossing behavior between the cavity and exciton modes, with measured Rabi splittings of 47 and 60 meV, respectively, both at 5 K and room temperature.