Reliable estimation of Raman shift and its uncertainty for a non‐doped Si substrate (NMIJ CRM 5606‐a)
Nobuyasu Itoh, Katsuhiro Shirono
Abstract
Abstract Raman shift is one of the most important parameters in Raman spectroscopy and is theoretically calculated from the difference in the wavenumbers of excitation and Raman scattering. At present, there are no standard procedures available to reliably estimate the Raman shift and evaluate its uncertainty from experimental results. In this study, we reliably estimated the Raman shift and evaluated its uncertainty for a non‐doped crystalline Si substrate (NMIJ CRM5606‐a) using a He‐Ne laser and its plasma lines (Ne emission lines). The Raman scattering wavenumber of NMIJ CRM 5606‐a was estimated by the bracket calibration method using the wavenumbers of the closest Ne emission lines. The Raman shift was determined from the differences in the theoretical wavenumbers of a He‐Ne laser and the observed Raman scattering. To evaluate the combined standard uncertainty, we considered the uncertainty originating from the He‐Ne laser and the Ne emission lines, the repeatability of experimental results, inhomogeneity of measuring points and spectral dispersion. The estimated Raman shift was 520.45 cm −1 ± 0.28 cm −1 (coverage factor k = 2). The Raman shift was validated by the other estimated Raman shifts obtained with other two Raman spectrometers.