InGaAs/GaAsP Superlattice Resonant Cavity-Enhanced Photodetector Fabricated on a Nominal Si(001) Substrate for Near- and Short-Wavelength Infrared Applications

Abstract

The III−V materials offer superior optoelectronic performance that makes them an attractive choice for integration into cheap and ubiquitous Si-based technologies, contingent upon addressing the consequences of the prohibitively large lattice constant mismatch between the two material systems. We present a near-infrared (NIR) resonant cavity-enhanced photodetector (RCE PD) monolithically integrated onto a nominal Si(001) substrate and incorporating a thin InGaAs/GaAsP strained-layer superlattice acting as the absorber, as well as five repetitions of GaAs/AlGaAs distributed Bragg reflectors providing resonant enhancement. The photodetector was metal− organic chemical vapor deposition-grown onto the Si(001) substrate using a buffer incorporating simultaneously a GaAs bulk layer and the distributed Bragg reflector (DBR) stack, a two-step growth temperature sequence, and an optimized thermal cycle annealing process, with a total structure thickness of 2.6 μm. The device demonstrates 13−21% internal quantum efficiency against the theoretical maximum of 39%, a result that is easily extendable via the addition of DBR pairs or other reflectors. Thanks to the thin absorber design inherent to the RCE PD architecture, the dark current density of the Si-based device is reduced to the same order of magnitude (∼10 −8 A cm −2 ) as an identical structure grown on a lattice-matched GaAs substrate. In general, the promising structural and optoelectronic results for this device represent a viable track to direct monolithic integration of III−V materials onto Si wafers, while the tunability of the InGaAs/GaAsP superlattice system opens up the potential for extended NIR and short-wavelength infrared coverage.