Mid-infrared intersubband electroluminescence from a single-period GaAs/AlGaAs triple barrier structure

This letter reports the observation of intersubband electroluminescence from a single-period resonant tunneling structure. Intersubband emission (λ≈8.4 μm), with a full width at half maximum of 7 meV, was observed from a GaAs/AlGaAs triple barrier structure with quantum well widths of 66 and 33 A. The emission was coupled out of the sample by a metallic grating with a period of 5 μm deposited on the surface. The intensity of emission follows the resonance behavior in the I–V characteristics. As the temperature increases from 10 to 200 K, the emission intensity decreases monotonically by a factor of ∼2 and the emission energy shifts down slightly (ΔE≈2.7 meV). The temperature dependence of the emission energy is explained by a combination of thermal broadening of the electron distribution and the nonparabolicity of the conduction bands.