InGaAsPN/InP based photodetectors for long wavelength (/spl lambda/>1.65 /spl mu/m) applications

InGaAsP alloys grown lattice matched to InP substrates are widely used for detectors at optical fiber communication wavelengths. For these detectors, the cutoff wavelength is 1.65 /spl mu/m as determined by the band gap of the lattice-matched In/sub 0.53/Ga/sub 0.47/As absorption layer. Detectors with In content larger than 53% have been fabricated, but exhibit higher dark currents due to defects in the relaxed, lattice-mismatched InGaAs layer. Recently, we demonstrated that incorporation of nitrogen into InGaAs may extend the wavelength of InP based photodetectors beyond 1.65 /spl mu/m. We report the first lattice matched InGaAsPN based photodetectors on InP with cutoff wavelengths extending to >1.89 /spl mu/m. In the study, a mesa PIN type photodetector structure with narrow band gap InGaAsPN as the absorption layer was grown on an n-type InP substrate by gas source molecular beam epitaxy (GSMBE).