Effect of InP epitaxial layer removal from an MOVPE reactor on in-situ Zn diffusion for the development of focal plane arrays

摘要

Diffusion of Zn in InP epitaxial layers, for application in the development of focal plane arrays using planar geometry, has been investigated. The InP layer has to go through a lithographic process between growth and diffusion, meaning it is exposed to air. We have verified that the surface reconstruction of the material is not affected by air exposure, even though the reconstruction anisotropy changes during diffusion, but it is reestablished once the diffusion is interrupted. On the other hand, the doping diffusion depth is shortened by about 30%, because the unavoidable oxide barrier formed on the surface directly affects the diffusion process. Unfortunately, exposure to air is necessary. Therefore, it is fundamental that diffusion conditions be optimized taking into account the air exposure step.