2.6 μm InGaAs photodiodes

Abstract
We have developed In0.82Ga0.18As pn homojunction photodiodes that have a long‐wavelength threshold at about 2.65 μm. A compositionally graded InxGa1−xAs layer accommodates the 2% lattice mismatch between the InP substrate and the In0.82Ga0.18As active layers of the device. At −2 V reverse bias the room‐temperature dark current is 3.5 μA (32 mA/cm2), and the quantum efficiency is 70–75% over the wavelength interval of 2.1–2.6 μm.