Design and characterization of resonant cavity enhanced Schottky photodiodes

Abstract

Recently, novel photodetectors which employ a multiple-pass detection scheme to increase the efficiency-bandwidth product have been developed. In this thesis. we present our work on .\iAs/GaAs resonant cavity enhanced (RCE) Schottky photodiodes w'ith an InGaAs absorber. Quantum efficiency enhancement is acconiplished by placing the InGaAs absorber inside a Fabry-Perot microcavity whose mirrors are formed b}' the Au Schottky layer cind an rVlAs/GaAs quarter wave stcick (QWS) reflector. In the design and analysis of the structures, scattering (S) matrices are used. Reflectivity, transmissivity, quantum efficiency, and the loss in the Schottky metal are calculated, a.nd it is shown that, it is ¡possible to diminish the front-surface reflectivity using a Si:iN.| dielectric coating to optimize the quantum efficiency. High speed and spectral efficiency/ measurements on fabricated photodiodes are also presented.