Zn diffusion technology for InP-InGaAs avalanche photodiodes

This paper presents a study of Zn diffusion process into InP and InGaAs/InP epitaxial heterostructures grown by molecular beam epitaxy. It was found that both diffusion systems: a resistively heated quartz reactor with a solid-state Zn vapor source placed inside and hydrogen or nitrogen as the carrier gas and MOCVD reactor with hydrogen as the carrier gas allow achieving similar dopant concentration above 2*10e18 cm-3. The depth of the diffusion front in the InP layer is located from 2 to 3.5 μm depending on the temperature and time of the diffusion process. The diffusion of Zn into InP through the intermediate InGaAs layer provides better surface quality comparing with direct zinc diffusion into InP surface.