Raman scattering and structural analysis of electrodeposited CuInSe₂ and S‐rich quaternary CuIn(S,Se)₂ semiconductors for solar cells

Abstract

This work reports the Raman scattering characterisation of CuInSe2 precursors grown by single step electrodeposition and the corresponding layers recrystallised under sulphurising conditions for solar cell devices. The analysis of the spectra measured on the as‐grown precursors has allowed identifying the main secondary phases in these layers with elemental Se, Cu–Se phases and chalcopyrite Cu‐poor ordered vacancy domains. To deepen in the identification of the Cu–Se phases, these measurements have been correlated with the analysis of binary Cu–Se layers. The experimental data indicate that formation of both Se and Cu–Se phases is likely controlled by the Se content in the layers. For values of stoichiometry below 1.15, excess Cu in the layers is accommodated in a phase with very low Raman efficiency (as Cu2Se). Increasing the content of Se leads to an increase in the spectral contribution from both Se and Cu2–x Se, being the formation of these phases likely favoured under high excess Se conditions. The characterisation of the corresponding recrystallised layers has allowed analysing the impact of the presence of the secondary phases in the as‐grown absorbers on the performance of the final solar cells. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

How small amounts of Ge modify the formation pathways and crystallization of kesterites

“…4a. At the surface, Cu x Se is clearly detected with all three excitation wavelengths, 22 in agreement with the EDX and XRD analysis. At the back side, ZnSe is observed when using 488 nm excitation 23 together with Sn-Se phases, 24 and a very weak and broad band that is tentatively attributed to amorphous CZTSe.…”

Growth and structural properties of pulsed laser-ablated CuInSe2 nanoparticles by pulsed-laser ablation and selenization process

“…4, all show the A 1 symmetry mode from chalcopyrite ordered at approximately 176 cm −1 . This is consistent with previous studies [25][26][27][28] where the most intense Raman peak was observed at approximately 175 cm −1 . This mode corresponds to anion Se movement with cations at rest.…”

“…The Raman spectra are also characterized by a broad feature centered at 240 cm −1 . This feature may be ascribed the chalcopyrite B 2 and E modes [28] and/or elemental Se at approximately 240 cm −1 [27]. That this feature is strongest for the 300 • C sample suggests existence of surplus Se in the CIS nanoparticles, but this surplus disappeared when the treatment temperature was increased.…”

Raman Spectroscopy on Thin Films for Solar Cells

“…Electrodeposition -based processes have interest because of their higher potential to achieve a significant reduction in fabrication costs in relation to standard physical vapor deposition (PVD) processes. This spectrum shows the presence of modes characteristic of both Cu-rich and Cupoor secondary phases, which coexist with the desired chalcopyrite-type phase [10]. The existence of chalcopyrite-type CuInSe 2 can be inferred from the observation of a characteristic A 1 band at 173 cm À1 .…”