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

A separated absorption and multiplication avalanche photodiode for light detection to wavelengths as long as 2.25~μm 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 μm at 250 K and increased to 20 at 77 K. A primary dark current of 2.2 × 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.