Demonstration of high-speed (Al,Ga)As/sub 0.51/Sb/sub 0.49//InP type-II uni-traveling carrier photodiodes for 1.55 /spl mu/m operation

We demonstrate staggered ("type-II") lineup lattice-matched GaAs/sub 0.51/Sb/sub 0.49//InP uni-traveling carrier photodiodes (UTC-PDs) for application near 1.55 /spl mu/m. The GaAsSb absorbing layer conduction band edge lines up /spl Delta/E/sub C/=0.11 eV above that of InP, and hence allows the direct injection of photo-generated electrons into an InP collector-without any need for compositional grading around the GaAsSb/InP interface-thus simplifying epitaxial growth and device fabrication. InP/GaAsSb UTC-PDs show low dark current levels, and measurable bandwidths are limited by the test equipment. A transit-limited bandwidth of 105 GHz for a PD with a 1000 /spl Aring/ GaAsSb absorption layer (C:5/spl times/10/sup 18//cm/sup 3/) and a 2000 /spl Aring/ InP collector is inferred from the variation of photoresponse bandwidth with device area.