GeSn short-wave infrared photodetectors

Ge photodetector (PD) is a key device in the Si-based photonics. But due to the limitation of the bandgap, Ge PD cannot cover the L-band (1565 nm-1625 nm) and U-band (1625 nm-1675 nm) telecommunication windows. The incorporation of Sn into Ge adjusts the band structures, and effectively shrinks the bandgap. This makes GeSn photodetector a promising device for short-wave infrared light detection covering the all telecommunication windows. In this paper, growth of GeSn alloys on Si and Ge substrates by MBE and sputtering will be introduced. GeSn PIN photodetectors were fabricated by CMOS compatible process. The performance of the GeSn PDs, such as dark current, response spectra and quantum efficiency will be presented and discussed.