Robust Hot‐Carrier‐Based Gallium Arsenide Photodetectors for 2 µm Optical Window

Recent advancements in fiber‐optic communication have established the conventional wavelength of 1550 nm. However, the next generation of telecommunications promises excellent prospects at 2 µm wavelengths via hollow‐core photonic‐bandgap fibers (HC‐PBGFs). Nevertheless, many semiconductors struggle to operate effectively at their intrinsic bandgap due to wavelength redshift. In this work, the gallium arsenide (GaAs) operating band is successfully extended to the 2 µm optical communication band using the GaAs Trench Metal (GATM) structure, enhancing absorptance and overall performance. Notably, the GATM device exhibits a photovoltage responsivity of 5.48 V W −1 under zero bias operation. This remarkable performance is attributed to the surface plasmonic effect and resonant cavity mode, resulting in approximately 3.8 times current gain and about 3 times voltage gain compared to flat film devices. Furthermore, the GATM devices demonstrate exceptional temperature stability, ranging from −195°C to 195°C, highlighting their potential for applications in harsh environments. These devices showcase stable and improved performance wiin the 2 µm optical communication band, ensuring reliable operation across a broad temperature range. Such characteristics make them well‐suited for advanced telecommunications technologies.