High-performance InGaAs photodetectors on Si and GaAs substrates

Abstract
In this work, we demonstrate record low dark current operation of InGaAs (1.55 μm) pin photodetectors on both silicon and gallium arsenide substrates using a wafer bonding technique. The photodetectors were made by first bonding the pin epitaxial layers to the Si and GaAs substrate followed by chemical removal of the host (InP) substrate from the pin structure. The photodetector was then fabricated atop the newly exposed pin 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 gave 17 Ω on GaAs and 350 Ω on Si, respectively.