Investigation of Germanium Photoconductive Antennas based on Flexible Substrates for Terahertz Detection

Abstract

Flexible electronics have been gaining increasing attention for next-generation optoelectronic applications. Yet, the use of flexible substrates in Terahertz (THz) Photoconductive Antennas (PCAs) remains unexplored - mainly because of the incompatibility of conventional photoconductive materials with polymeric substrates. Recently emerged Germanium (Ge) thin film-based PCAs have advantages such as CMOS compatibility and adaptability to various platforms. We employed a Kapton substrate for a bowtie Ge-PCA and investigated its potential as a Terahertz (THz) detector. The antenna is made of a Sputtered-Ge film with a Gold-Germanium (AuGe) electrode having a gap of ~ 3 µm. A comparison between Ge-on-Glass and Ge-on-Kapton PCAs is drawn. The bandwidth reached up to 1.8 THz, and with an SNR of 30 dB, we show the compatibility of flexible substrates for PCAs in THz detection. These preliminary results take a step towards conformal THz sensing using Ge-PCAs. © 2025 IEEE.