Highly Integrated Ultra-Low Leakage Current Shortwave Infrared Photodetector Based on Ge-Si Heterogenous Wafer Bonding

A shortwave infrared photodetector based on Ge-Si heterojunction is proposed and fabricated by the innovative combination of epitaxy and wafer bonding method. This structure achieves excellent charge transport through the heterogenous mismatched interface with low carrier recombination. Ultra-low leakage current density of 0.65 mA/cm2 is realized at 300 K with perfect saturation trend under higher reverse bias, indicating a strong ability to respond to extremely weak light signal. Optical responsivity at 1550 nm wavelength is 0.33 A/W, 3-dB bandwidth reaches 22.5 GHz and a clear open eye diagram at 50 Gbps is demonstrated, confirming the distinguished comprehensive performance of this photodetector. Due to the highly integration of the photodetector on Si and its compatibility with CMOS technology, optical interconnection with integrated circuits is able to realize for lower loss, faster transmission speed, larger scale and more versatile optoelectronic chips.