Resonant-cavity GaAs/InGaAs/AlAs photodiodes with a periodic absorber structure

Abstract
Resonant‐cavity photodiodes with a periodic absorber structure are demonstrated. The photodiode consists of three thin InGaAs absorbing layers located at the antinodes of standing wave optical field in a resonant cavity. The bottom mirror of the resonant cavity is formed by a GaAs/AlAs quarter‐wave stack, while the top mirror is formed by the GaAs/air interface. Theoretical estimation based on the standing wave effect gives 70% peak quantum efficiency at the resonant wavelength. The peak quantum efficiency of this photodiode, as measured by a calibrated Si photodetector, enhanced by 30% as compared to a conventional resonant‐cavity photodiode with a single absorbing layer of the same overall thickness. The observed enhancement in quantum efficiency is consistent with theory.