GeSn Waveguide Photodetectors with Vertical p- i- n Heterostructure for Integrated Photonics in the 2 mu m Wavelength Band

The 2 mu m wavelength band (1800-2100 nm) emerges as a promising candidate for next-generation optical communication. As a result, silicon photonic platforms acquire great interest since they offer the ultimate minimization of photonic systems for 2 mu m band applications. However, the large bandgap and indirectness of the band structure of the conventional SiGe alloy prevent their utilization for efficient photodetection in the 2 mu mwavelength band. To overcome this drawback, complementary metal-oxide semiconductor (CMOS)-compatible GeSn waveguide photodetectors (WGPDs) with a vertical p- i- n heterojunction configuration that can operate in the 2 mu m wavelength band is demonstrated. The proposed photodetector incorporates 5.28% Sn into the GeSn active layer, which redshifts the photodetection range to 2090 nm. In addition, the longer light-matter interaction length and good optical confinement of the proposed GeSn WGPD enhance the optical responses significantly. As a result, the proposed GeSn WGPD achieves a responsivity up to 0.52 AW(-1) and a detectivity up to 7.9 x 10(8) cm Hz(1/2) W-1 in the 2 mu m wavelength band at room temperature. These promising results indicate that the developed GeSn WGPDs are promising candidates for integrated photonics in the 2 mu m wavelength band.