Zinc diffusion process investigation of InP-based test structures for high-speed avalanche photodiode fabrication

The characterization of zinc diffusion processes for three different test structures has been investigated. The comparison between the different diffusion process conditions for different test structures were explored. The zinc diffusion profiles, such as the diffusion depth and the zinc dopant concentration, were examined using secondary ion mass spectrometry with varying the amount of Zn₃P₂ source, the ampoule volume, and the diffusion time. It is observed that the diffusion profiles are severely impacted on the process parameters, such as the amount of Zn₃P₂ source, the ampoule volume, and the diffusion time, as well as material parameters, such as doping concentration of the diffusion layer. These results from the Zn diffusion process can be utilized for the high-speed InP/InGaAs avalanche photodiodes fabrication.