m-plane GaN split-well direct-phonon terahertz quantum cascade laser.

Area of Science:

• Semiconductor Physics
• Quantum Electronics
• Materials Science

Background:

• Terahertz quantum cascade lasers (THz QCLs) are crucial for various applications.
• Existing GaN-based THz QCL designs face challenges in balancing gain and current density, risking thermal damage.
• Operating THz QCLs at higher frequencies and temperatures remains a significant goal.

Purpose of the Study:

• To theoretically investigate a novel GaN-based THz QCL structure using the split-well direct-phonon (SWDP) scheme.
• To address limitations in previous designs by reducing doping density and current requirements while maintaining high gain.
• To explore the potential for high-frequency, room-temperature THz QCL operation.

Main Methods:

• Theoretical investigation of a GaN-based THz QCL structure.
• Modeling growth along the non-polar m-plane.
• Analysis using the Non-equilibrium Green's Function (NEGF) approach.
• Implementation of the split-well direct-phonon (SWDP) scheme with a modified well structure.

Main Results:

• The proposed m-plane SWDP GaN-based design achieves optical gain comparable to state-of-the-art devices.
• Significantly lower current densities, comparable to mid-infrared QCLs, were achieved by reducing doping density.
• The device operates at ~7.9 THz, exceeding typical GaAs-based QCL limits, and maintains gain above losses up to room temperature.

Conclusions:

• The m-plane SWDP GaN-based design offers a promising route for high-frequency, high-temperature THz QCLs.
• The design provides practical guidelines for future experimental realization of advanced THz QCLs.
• This work paves the way for more robust and efficient terahertz technology.