Mid-Infrared Hole-Intersubband Electroluminescence in Carbon- Doped GaAs/AlGaAs Quantum Cascade Structures

Mid-infrared electroluminescence from carbon-doped GaAs/AlGaAs quantum cascade structures was observed and studied to determine the prospects of hole intersubband transitions for possible use in light emitting devices. The luminescence spectra exhibit a complex three-peak structure consistent with two heavy-to- heavy hole transitions and thermal emission. The hole transition energies in emission are in agreement with corresponding absorption and photocurrent energies, but typically 17% smaller than expected from calculations of a six-band k•p model. The upper-level lifetime was estimated to be 0.4 ps, in agreement with simple calculations considering approximations of the heavy-hole effective masses. The dominant heavy-to-heavy hole transition broadens from 20 to 45 meV with increasing injection current.