Enhanced photoluminescence emission from two-dimensional silicon photonic crystal nanocavities

TL;DR

This study investigates temperature-dependent photoluminescence in silicon nanocavities, revealing enhanced emission stability at higher temperatures likely due to the Purcell effect, with implications for silicon photonics.

Contribution

It demonstrates room-temperature cavity mode emission in silicon nanocavities and suggests Purcell-enhanced quantum efficiency as the cause.

Findings

Cavity mode emission persists up to room temperature.

Defect band luminescence is localized to etched regions.

Temperature dependence indicates Purcell effect enhances emission stability.

Abstract

We present a temperature dependent photoluminescence study of silicon optical nanocavities formed by introducing point defects into two-dimensional photonic crystals. In addition to the prominent TO phonon assisted transition from crystalline silicon at ~1.10 eV we observe a broad defect band luminescence from ~1.05-1.09 eV. Spatially resolved spectroscopy demonstrates that this defect band is present only in the region where air-holes have been etched during the fabrication process. Detectable emission from the cavity mode persists up to room-temperature, in strong contrast the background emission vanishes for T > 150 K. An Ahrrenius type analysis of the temperature dependence of the luminescence signal recorded either in-resonance with the cavity mode, or weakly detuned, suggests that the higher temperature stability may arise from an enhanced internal quantum efficiency due to the Purcell-effect.