Improved spectral brightness of 5.2 μm plasmonic resonant-cavity LEDs with light extraction through substrate

We report the development of resonant-cavity light-emitting diodes featuring emission through the substrate and high spectral power density at 5.2 μm wavelength. By utilizing a thin doped semiconductor layer to create a microcavity around a multi-quantum-well “W”-structured type II active region, the device shows a 55% reduction in full width at half maximum of its emission spectrum relative to that of a conventional light-emitting diode with the same active region. Resonant-cavity devices demonstrate stable continuous-wave operation at room temperature and a power spectral density per unit area of 0.13 mW/(nm cm2) at 5.2 μm, approximately a factor of 2.5 higher than that of reference devices without the resonant cavity.