High-performance evanescently edge coupled photodiodes with partially p-doped photoabsorption layer at 1.55-μm wavelength

In this letter, we demonstrate a high-performance evanescently coupled photodiode (ECPD) with the partially p-doped photoabsorption layer. As compared to the control ECPD with the traditional intrinsic photoabsorption layer, the demonstrated device can exhibit much higher output saturation current (power) and electrical bandwidth without sacrificing the quantum efficiency performance. By properly designing the geometry size and epilayer structures of the partially p-doped ECPD, very high responsivity (1.01 A/W), high electrical bandwidth (around 50 GHz), and high saturation current bandwidth product (920 mA. GHz, at 40 GHz) have been achieved simultaneously at 1.55-μm wavelength.