Engineering of electron–longitudinal optical phonon coupling strength in m-plane GaN terahertz quantum cascade lasers. (13th October 2021)

• Record Type: Journal Article
• Authors: Wang, Li; Lin, Tsung-Tse; Chen, Ming-Xi; Wang, Ke; Hirayama, Hideki
• Is Part Of: Applied physics express. Volume 14:Number 11(2021)
• Publication Date: 2021-10-13
• Subjects: GaN -- quantum cascade laser -- terahertz -- quantum transport -- semiconductor; Physics -- Periodicals; Technology -- Periodicals; 621.05
• DOI: 10.35848/1882-0786/ac2a02
• Languages: English
• ISSNs: 1882-0778

Abstract

Abstract: In this work nonpolar ( m -plane) GaN terahertz quantum cascade lasers are designed based on the non-equilibrium Green's function method. The lasing quantum-level broadening that arises from electron– longitudinal optical (LO) phonon coupling is studied by tuning the coupling strength, and the changes of optical gain due to this broadening are demonstrated in a self-consistent way. It is found this coupling process largely widens the linewidth of intersubband transition and then quenches the lasing even at a low temperature of 10 K. The electron–LO phonon coupling strength, however, can be manually engineered by tailoring the quantum well structure. As a result, the optical gain will be recovered above the cavity threshold, indicating a potential for terahertz lasing from GaN semiconductors.