# Measuring thickness in thin NbN films for superconducting devices

## TL;DR

This paper demonstrates a rapid, accurate method using multi-wavelength ellipsometry to measure NbN thin film thicknesses, improving fabrication and performance of superconducting nanowire single photon detectors.

## Contribution

It introduces a commercially available ellipsometry technique for precise, non-destructive thickness measurement and optical constant determination of NbN films.

## Key findings

- Accurate thickness measurements of NbN films achieved
- Oxidation growth observed and monitored
- Process integration enhances device fabrication

## Abstract

We present the use of a commercially available fixed-angle multi-wavelength ellipsometer for quickly measuring the thickness of NbN thin films for the fabrication and performance improvement of superconducting nanowire single photon detectors. The process can determine the optical constants of absorbing thin films, removing the need for inaccurate approximations. The tool can be used to observe oxidation growth and allows thickness measurements to be integrated into the characterization of various fabrication processes.