InGaAsPN/InP based photodetectors for long wavelength (λ>1.65 μm) 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 μm as determined by the band gap of the lattice-matched In_0.53Ga_0.47As 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 μm. We report the first lattice matched InGaAsPN based photodetectors on InP with cutoff wavelengths extending to >1.89 μm. 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)