Mid-infrared field-tunable intersubband electroluminescence at room temperature by photon-assisted tunneling in coupled-quantum wells

Electroluminescence associated with intersubband transition energies greater than the optical phonon energy and at temperatures as high as 300 K is reported. The mid-infrared (λ∼5 μm) luminescence is generated by electron injection into AlInAs/GaInAs coupled-quantum wells via an AlInAs/GaInAs pseudoquaternary graded gap alloy. Optical powers up to a few nanowatts and linear in the drive current have been measured. The large Stark shift of the luminescence peak demonstrates the photon-assisted tunneling nature of the transition. The temperature independence of the luminescence slope efficiency in the 10–100 K range and the linearity of the optical power versus drive current provide strong evidence of population inversion.