Split-well resonant-phonon terahertz quantum cascade laser

Area of Science:

• Semiconductor Physics
• Optoelectronics
• Quantum Electronics

Background:

• Terahertz quantum cascade lasers (THz-QCLs) are crucial for various applications.
• Improving the temperature performance and operational stability of THz-QCLs remains a significant challenge.
• Existing designs often suffer from thermally activated leakage channels, limiting device performance.

Purpose of the Study:

• To introduce and evaluate a novel "split-well resonant-phonon" (SWRP) active region design for GaAs/Al0.3Ga0.7As THz-QCLs.
• To investigate the temperature performance and potential of the SWRP design.
• To demonstrate the suppression of leakage channels at room temperature.

Main Methods:

• Fabrication and characterization of THz-QCLs utilizing the SWRP active region design.
• Analysis of current-voltage (I-V) characteristics to identify negative differential resistance (NDR).
• Comparison of SWRP design with the conventional split-well direct-phonon (SWDP) design.

Main Results:

• Observation of negative differential resistance (NDR) at room temperature, signifying suppressed leakage.
• Reduced overlap between the doped region and active level states in the SWRP design compared to SWDP.
• Maintained a 36 meV energy gap between the lower laser level (LLL) and injector for efficient LLL depopulation.

Conclusions:

• The SWRP active region design effectively suppresses thermally activated leakage channels in THz-QCLs.
• The design shows promising potential for enhanced temperature performance and operational stability.
• Further investigation into the temperature performance and optimization of the SWRP structure is warranted.