Simplifying <i>in vacuo</i> optical measurements of CVD processes using vacuum-compatible optical fibers

In situ optical measurements during chemical vapor deposition processes can offer insight into the chemical reactions and electronic phenomena that are occurring during a process. However, the tooling to make these measurements can be complex, difficult to align, and may even require a redesign of the entire vacuum deposition chamber. Herein, we present a setup that allows for in situ optical measurements using vacuum-compatible fiber optics that only requires a singular conflat feedthrough, eliminating the need for optical viewports and alignment of external light sources/detectors. Proof of performance is shown with a neutral density filter and an exemplary application of vapor doping a conjugated polymer (poly-3-hexylthiophene) using vapor-phase TiCl4.