Substrate‐independent analysis of microcrystalline silicon thin films using UV Raman spectroscopy

Abstract

Surface‐sensitive UV Raman spectroscopy is used to analyze the crystallinity of silicon films less than 20 nm thick directly on silicon wafers. The 325‐nm excitation has a Raman detection thickness of only 13 nm within the silicon film, thus eliminating signal from the substrate. We demonstrate measured crystallinities of microcrystalline silicon thin films that are consistent with the microstructure observed in transmission electron microscopy. Comparison is also made to ellipsometry, which is less able to accurately determine crystallinity than UV Raman spectroscopy. The UV Raman approach is particularly useful for layers grown on substrates of the same material but with different microstructure, and can be extended to non‐silicon materials.

Interdigitated back contact silicon heterojunction solar cells featuring an interband tunnel junction enabling simplified processing

“…510 nm -1 and 520 nm -1 ), as proposed by (Vallat-Sauvain et al, 2006). Note that the penetration depth of the 515 nm laser used here in nc-Si:H is of about 50 nm (Carpenter et al, 2017), which is comparable to the typical thickness of the nc-Si:H layers under investigation.…”

Influence of the Dopant Gas Precursor in P-Type Nanocrystalline Silicon Layers on the Performance of Front Junction Heterojunction Solar Cells

“…Raman spectra of nc-Si:H layers were acquired directly on the wafer on areas uncovered by TCO. To avoid the contribution of the c-Si and the a-Si:H(i) layer underneath, a 325 nm UV laser was used to probe only the top 10-15 nm of the layers [35]. To obtain an accurate background shape and extract the crystalline and amorphous phase features, Raman spectra were fitted with Gaussians centered around 315, 420, 480, 510, 520 and 625cm -1 [36].…”