Two-well injector direct-phonon terahertz quantum cascade lasers

We present an experimental study on a terahertz quantum cascade laser (THz QCL) design that combines both two-well injector and directphonon scattering schemes, i.e., a so-called two-well injector direct-phonon design. As a result of the two-well injector direct-phonon scheme presented here, the lasers benefit from both a direct phonon scattering scheme for the lower laser level depopulation and a setback for the doping profile that reduces the overlap of the doped region with active laser states. Additionally, our design also has efficient isolation of the active laser levels from excited and continuum states as indicated by negative differential resistance behavior all the way up to room temperature. This scheme serves as a good platform for improving the temperature performance of THz QCLs as indicated by the encouraging temperature performance results of the device with a relatively high doping level of 7.56 x 10(10) cm(-2) and Tmax similar to 167 K. With the right optimization of the molecular beam epitaxy growth and interface quality, the injection coupling strength, and the doping density and its profile, the device could potentially reach higher temperatures than the latest records reached for the maximum operating temperature (T-max) of THz QCLs.

Automated summary

We conducted an experimental study on a new design for a terahertz quantum cascade laser (THz QCL) that combines two-well injector and direct-phonon scattering schemes. This design improves the performance of the lasers by using a direct phonon scattering scheme for depopulating the lower laser level and reducing the overlap with the doped region. The design also achieves efficient isolation of active laser levels and shows potential for higher operating temperatures than the current records.