Improvement of operation temperature in GaAs/AlGaAs THz-QCLs by utilizing high Al composition barrier.

Terahertz quantum cascade lasers (THz-QCLs) are compact THz laser source with narrow emission linewidth and high output power. Currently, a maximum operation temperature ( Tmax) of 199.5 K is reported by using a state-of-the-art longitudinal optical (LO) phonon depopulation scheme AlGaAs/GaAs structure. We propose an effective method to obtain higher operating temperature for AlGaAs/GaAs THz-QCL by increasing LO-phonon scattering energy by utilizing high Al composition AlGaAs barrier. We have successfully fabricated an LO phonon depopulation scheme AlGaAs/GaAs THz-QCL with double metal waveguide, and obtained 3.7 THz lasing. We obtained the Tmax of 150 K. We observed an increase of Tmax by about 7 K by increasing the Al composition of AlGaAs barrier from 15% to 30%. The characteristic temperature ( T0) was also improved from 44.7 K to 69.9 K by changing the Al composition of AlGaAs barriers. The increase of Al composition in AlGaAs-based THz-QCL was shown to be promising way for obtaining higher operating temperature of THz-QCL. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]