A novel GaInAs/GaAs Heterostructure Interdigital Photodetector (HIP) Using Lattice Mismatched Epitaxial Layers

Planar high-speed interdigital photoconductive detectors have been fabricated on MOCVD-grown GaInAs/GaAs heterostructures. The small intentional lattice mismatch at the GaInAs/GaAs interface allows a controlled surface recombination velocity which decreases the effective lifetime of minority carriers without significant active layer mobility degradation. The InGaAs detectors have the following characteristics: bandgap of ~ 1.25 eV; rise times of < 25 psec; fall times ~ 50-100 psec; FWHM < 45 psec; high speed responsivity ~0.3 A/W; 2-300 nA leakage current at 5-10 V operating voltages and flat analog response to ~ 15 GHz.