High-performance InGaAs photodetectors on Si and GaAs substrates

In this work, we demonstrate record low dark current operation of InGaAs (1.55 mu m) p-i-n 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 substrate followed by chemical removal of the host (InP) substrate from the p-i-n structure. The photodetector was then fabricated atop the newly exposed p-i-n 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 mu m 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 Ohm on GaAs and 350 Ohm on Si, respectively. (C) 1995 American Institute of Physics.