2.25- $\mu$ m Avalanche Photodiodes Using Metamorphic Absorber and Lattice-Matched Multiplier on InP

A separated absorption and multiplication aval-anche photodiode for light detection to wavelengths as long as $2.25~\mu \text{m}$ is reported. Photons were absorbed in a metamorphic In 0.75 Ga 0.25 As layer, while the photo-generated electrons were injected into a lattice-matched In 0.52 Al 0.48 As multiplier on InP. A responsivity gain of 2.7 was attained at 2 $\mu \text{m}$ at 250 K and increased to 20 at 77 K. A primary dark current of $2.2 \times 10^{-3}$ A/cm 2 at −15 V was measured at 77 K, which is dominated by dislocation defect-assisted tunneling with activation energies between 0.1 and 0.2 eV. This letter demonstrates the potentiality of extending spectral range of avalanche photodiodes in metamorphic device architecture.