Extended-wavelength InGaAs detectors grown by metal-organic vapor phase epitaxy (MOVPE) on compliant substrates

Current extended wavelength InGaAs detectors (<1 .7 pm) grown on InP are limited by the lattice-mismatch and consequent introduction of dislocations in the absorbing layer. In order to overcome these limits, GaAs based compliant substrates have been introduced for the growth of extended wavelength InGaAs detectors. In a first stage up to 3.8% lattice-mismatched InGaAs growth by MOVPE on GaAs compliant substrates has been investigated. Cross-hatch free surface morphology is obtained for epilayers with a thickness exceeding up to 50times the Matthews-Blakeslee critical thickness. X-ray diffraction (XRD) indicates a reduced FWHM (Full Width Half Maximum) and tilting of the InGaAs lattice-mismatched epitaxial layers, thus suggesting a reduced misfit dislocation density (at the interface). Consequently highly mismatched (5-6%)and thick (1-2 tim) InGaAs layers for the development of InGaAs detectors up to 2.5 jim, were grown on GaAs compliant substrates. Dark current measurements on the InGaAs detectors developed on compliant substrates indicate a comparable dark current level as for ordinary GaAs substrates, but a significant improvement in dark current uniformity. Current research includes the fabrication and use of dual material compliant substrates, e.g. InGaAs layers bonded on GaAs or other host substrates (Ge, .. .), for the growth of less than 2-3% latticemismatched InGaAs based detectors.