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

Abstract

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 1 -thick micro-cavity containing an InAs0.90Sb0.1 active region sandwiched between two high contrast, lattice-matched AlAs0.08Sb0.92/GaSb distributed Bragg reflector (DBR) mirrors. The electroluminescence emission spectra of the RCLED were measured 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 ~ x33. This is the highest resonant cavity enhancement ever reported for a mid-infrared LED operating at this wavelength. Furthermore, the RCLED also exhibits superior temperature stability ~0.35 nm/K and a significantly narrower (10x) 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.

Mid-infrared resonant cavity light emitting diodes operating at 4.5 µm

“…7(b) levels off above 260 K due to broadening of the QWs emission. Our results also show a greater intensity enhancement factor compared to previous work [28,34,35].…”

“…At room temperature, the results exhibited a single-lobe emission profile with a half power solid angle of 45 o as illustrated in Fig. 5, showing a better directionality compared with that of our previous work [35].…”

“…The total thickness of the completed RCLED structure is around 13 μm. Numerical modelling was used to evaluate the emission enhancement of the full resonant-cavity structure and the reflectivity of the top and bottom DBR mirrors based on our previous work [35]. The quality factor (Q), the emission rate enhancement at the resonance wavelength (G e ) and the integrated emission enhancement ( ) can be derived as: [36]…”

“…However, for the RCLED, the electroluminescence peak position also depends on the microcavity resonant optical mode, which is determined by the thickness and the refractive index of the materials forming the cavity. Based on our previous work [35], the thickness variation of the cavity was calculated as a function of temperature and accounts for less than 4% of the total wavelength shift, so that the main contribution originates from the temperature variation of the refractive index [44,45]. Consequently, the main electroluminescence emission peak of the RCLED shifts by only ~102 nm at a rate of 0.36 nm/K, while the peak of the reference LED shifts by ~600 nm at a rate of ~2.45 nm/K.…”

The Interband Cascade Laser

“…This has the effect of enhancing the emission rate due to a higher optical field at the antinodes of the cavity, while improving the directionality of the output and narrowing the emission spectrum. U. Lancaster recently applied this architecture to non-cascaded mid-IR LEDs with InAsSb alloy active regions [193].…”