A GaAs Schottky-barrier photodiode with high quantum efficiency-bandwidth product using a multilayer reflector

A GaAs Schottky-barrier with high quantum efficiency-bandwidth product has been developed by using a GaAs/Al/sub 0.25/Ga/sub 0.75/As multilayer reflector. The multilayer reflector structure wa designed by using the scattering matrix method. By growing four pairs of Al/sub 0.25/Ga/sub 0.75/As (825 AA)/GaAs (330 AA) multilayer reflectors between the undoped GaAs active layer and the buffer layer, a responsivity of 0.6 A/W at lambda =0.84 mu m was obtained 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.<
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