Electroluminescence enhancement in mid-infrared InAsSb resonant cavity light emitting diodes for CO₂ detection

In this work, we demonstrated a mid-infrared resonant cavity light emitting diode (RCLED) operating near $4.2$μm at room temperature, grown lattice-matched on a GaSb substrate by molecular beam epitaxy, suitable for CO₂ gas detection. The device consists of a $1λ$-thick microcavity containing an InAs_0.90Sb_0.1 active region sandwiched between two high contrast, lattice–matched AlAs_0.08Sb_0.92/GaSb distributed Bragg reflector (DBR) mirrors. The electroluminescence emission spectra of the RCLED were recorded over the temperature range from $20$ to $300$ K and compared with a reference LED without DBR mirrors. The RCLED exhibits a strong emission enhancement due to resonant cavity effects. At room temperature, the peak emission and the integrated peak emission were found to be increased by a factor of $∼70$ and $∼11$⁠, respectively, while the total integrated emission enhancement was $∼×33$⁠. This is the highest resonant cavity enhancement ever reported for a mid-infrared LED operating at this wavelength. Furthermore, the RCLED also exhibits a superior temperature stability of ∼$0.35$ nm/K and a significantly narrower (10×) spectral linewidth. High spectral brightness and temperature stable emission entirely within the fundamental absorption band are attractive characteristics for the development of next generation CO₂ gas sensor instrumentation.