Multilayer reflectors by molecular-beam epitaxy for resonance enhanced absorption in thin high-speed detectors

Abstract

The spectral responses of resonantly enhanced photodiodes are analyzed theoretically and verified experimentally. The quantum efficiency of a Schottky photodiode with a 50-nm AlInAs Schottky contact layer and a 475-nm GaInAs absorbing layer can be enhanced 1.5-fold by using a 16-layer quarter wave stack (QWS) of alternating Al0.17Ga0.30In0.53As and Al0.48In0.52As. The enhancement can be further improved if more periods of QWS are incorporated, or the substrate is selectively removed. The resonance width is approximately 60 nm. This type of structure should be very valuable for very small size ultrafast photodiodes and for optoelectronic integration.