Anomalous Temperature Effect in Weakly Coupled Superlattices: Carrier Transport in a THz Quantum Cascade Laser.

We present an investigation into the vertical transport through 13 different superlattice structures, where the well and barrier widths, doping concentration, dopant position, and contact layers were varied. Although superlattices have been extensively studied since 1970, there is a lack of publications on transport through superlattices similarly low doped as THz quantum cascade lasers (QCLs), for which the doping is in the 3-5×10^{10}  cm^{-2} range. The superlattices presented are doped in the same range as THz QCLs, with contact layers and fabrication comparable to high-temperature THz QCLs.

Ultrabroadband Heterogeneous THz Quantum Cascade Laser.

Broadband emission in the terahertz spectral region is a prerequisite for applications such as spectroscopy or white light sources. Appropriate signal powers and a compact design are advantageous for this use. A technology which meets these requirements are terahertz quantum cascade lasers.