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 $\text{(λ≈8.4\hspace{0.17em}μ}\mathrm{m}\mathrm{),}$ 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 Å. 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 $\mathrm{I–V}$ characteristics. As the temperature increases from 10 to 200 K, the emission intensity decreases monotonically by a factor of $\text{∼2}$ and the emission energy shifts down slightly $\text{(ΔE≈2.7\hspace{0.17em}}\mathrm{meV}\mathrm{).}$ 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.