Strain Compensated InGaAs/AlAs Triple Barrier Resonant Tunneling Structures for THz Applications

We report a theoretical study of InGaAs/AlAs triple barrier resonant tunneling heterostructures, which are optimized for operation in the terahertz frequency range, and compare these to current state-of-the-art double barrier structures reported in the literature. We consider the effect of strain introduced due to the large lattice mismatch between the substrate, quantum well, and potential barrier materials and describe designs with strain compensated active regions. Constraints have been imposed on the designs to minimize charge accumulation in the emitter quantum well, which is often associated with more complex triple barrier structures. The use of a triple barrier structure suppresses the off-resonance leakage current, thus increasing the maximum output power density, with ≈3 mWμm
^-2
predicted at 1 THz. The use of thinner potential barriers also reduces the carrier transit time through the structure, which increases the maximum output frequency, predicted to be ≥4 THz for optimized structures.