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

The III-V materials offersuperior optoelectronic performancethat makes them an attractive choice for integration into cheap andubiquitous Si-based technologies, contingent upon addressing the consequencesof the prohibitively large lattice constant mismatch between the twomaterial systems. We present a near-infrared (NIR) resonant cavity-enhancedphotodetector (RCE PD) monolithically integrated onto a nominal Si(001)substrate and incorporating a thin InGaAs/GaAsP strained-layer superlatticeacting as the absorber, as well as five repetitions of GaAs/AlGaAsdistributed Bragg reflectors providing resonant enhancement. The photodetectorwas metal-organic chemical vapor deposition-grown onto theSi(001) substrate using a buffer incorporating simultaneously a GaAsbulk layer and the distributed Bragg reflector (DBR) stack, a two-stepgrowth temperature sequence, and an optimized thermal cycle annealingprocess, with a total structure thickness of 2.6 & mu;m. The devicedemonstrates 13-21% internal quantum efficiency against thetheoretical maximum of 39%, a result that is easily extendable viathe addition of DBR pairs or other reflectors. Thanks to the thinabsorber design inherent to the RCE PD architecture, the dark currentdensity of the Si-based device is reduced to the same order of magnitude(& SIM;10(-8) A cm(-2)) as an identicalstructure grown on a lattice-matched GaAs substrate. In general, thepromising structural and optoelectronic results for this device representa viable track to direct monolithic integration of III-V materialsonto Si wafers, while the tunability of the InGaAs/GaAsP superlatticesystem opens up the potential for extended NIR and short-wavelengthinfrared coverage.