A GAAS SCHOTTKY-BARRIER PHOTODIODE WITH HIGH QUANTUM EFFICIENCY BANDWIDTH PRODUCT BY USING A MULTILAYER REFLECTOR

A GaAs Schottky-barrier photodiode with high quantum efficiency-bandwidth product has been developed by using a GaAs/Al0.25Ga0.75As multilayer reflector. The multilayer reflector structure was designed by using the scattering matrix method. By growing four pairs of Al0.25Ga0.75As (825 angstrom)/GaAs (330 angstrom) multilayer reflectors between the undoped GaAs active layer and the buffer layer, we obtained a responsivity of 0.6 A/W at lambda = 0.84 mum for this device. This represents a 30% improvement over the device without a multilayer reflector. The response speed of the photodiode was measured by the impulse response method, and the results yielded a rise time of 38.45 ps, corresponding to a bandwidth of 9 GHz for this detector.