Bias-free GeSn terahertz large area emitter on Si substrate

Chia-Wei Chang; Wang-Chien Chen; Shang-Hua Yang

doi:10.1117/12.2631706

30 September 2022 Bias-free GeSn terahertz large area emitter on Si substrate

Chia-Wei Chang, Wang-Chien Chen, Shang-Hua Yang

Proceedings Volume 12230, Terahertz Emitters, Receivers, and Applications XIII; 1223007 (2022) https://doi.org/10.1117/12.2631706
Event: SPIE Optical Engineering + Applications, 2022, San Diego, California, United States

Abstract

In the past decades, terahertz (THz) large area emitters (LAEs) have been used for broadband THz generation. To achieve broadband operation, the ultrafast photoconductor of THz LAE is mainly based on III-V semiconductor materials, which is designed to offer decent quantum efficiency, high carrier mobility, and low carrier lifetime simultaneously. However, the sophisticated epitaxial process constrains the application scopes of conventional THz LAEs. Here, we present a cost-effective, CMOS-compatible, bias-free GeSn THz LAE on a Si substrate. The GeSn thin film is grown on undoped Si substrate with Ge buffer layer by reduced pressure chemical vapor deposition (RPCVD). Since the charge neutrality level is close to the top of the valence band, a built-in electric field at the surface of GeSn is created by the fermi-level pinning. As the optical absorption coefficient of the GeSn ultrafast photoconductor is higher than 7000 cm^-1 in the 1500 – 1700 nm wavelength range, it can generate a comparable amount of photocarriers as InGaAs-based ultrafast photoconductor. To investigate the broadband operation capability of the bias-free GeSn THz LAE prototypes, we further characterize the carrier dynamics of the epitaxial GeSn thin film. At the optical pump power of 400 mW, the bias-free GeSn THz LAE generates broadband THz radiation with a pulse width of 500 fs full width at half maximum. The GeSn THz LAE can be monolithically integrated on Si photonic platform with the bias-free operation. It paves the way toward THz system-on-chip (SoC) for many on-site applications in non-destructive evaluation, biomedical imaging, and industrial inspections.

Conference Presentation

Citation Download Citation

Chia-Wei Chang, Wang-Chien Chen, and Shang-Hua Yang "Bias-free GeSn terahertz large area emitter on Si substrate", Proc. SPIE 12230, Terahertz Emitters, Receivers, and Applications XIII, 1223007 (30 September 2022); https://doi.org/10.1117/12.2631706

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available