High-performance InGaAs photodetectors on Si and GaAs substrates

In this work, we demonstrate record performance operation of long wavelength (1.55 μm) P-I-N (InP-InGaAs-InP) photodetectors on both Silicon and Gallium Arsenide substrates using a wafer bonding technique. The photodetectors were made by first bonding the P-I-N epitaxial layers to the Si and GaAs substrates followed by chemical removal of the host (InP) substrate from the P-I-N structure. The photodetectors were then fabricated atop the newly exposed P-I-N (InP-InGaAs-InP) epilayers. Dark currents of as low as 57 pA on a GaAs substrate and 0.29 nA on a Si substrate were measured under 5 V reverse bias. The responsivity at 1.55 μm wavelength was measured to be 1 A/W, corresponding to an external quantum efficiency of 80%. The series resistance measured across the bonded interface and P-I-N layers gave 17 Ω on GaAs and 350 Ω on Si, respectively