TY - JOUR
T1 - Optical characterization of poly-SiOx and poly-SiCx carrier-selective passivating contacts
AU - Singh, M.
AU - Santbergen, R.
AU - Mazzarella, L.
AU - Madrampazakis, A.
AU - Yang, G.
AU - Vismara, R.
AU - Remes, Z.
AU - Weeber, A.
AU - Zeman, M.
AU - Isabella, O.
PY - 2020
Y1 - 2020
N2 - The optical modelling for optimizing high-efficiency c-Si solar cells endowed with poly-SiOx or poly-SiCx carrier-selective passivating contacts (CSPCs) demands a thorough understanding of their optical properties, especially their absorption coefficient. Due to the mixed phase nature of these CSPCs, spectroscopic ellipsometry is unable to accurately detect the weak free carrier absorption (FCA) at long wavelengths. In this work, the absorption coefficient of doped poly-SiOx and poly-SiCx layers as function of oxygen and carbon content, respectively, was obtained for wavelengths (300–2000 nm) by means of two alternative techniques. The first approach, photothermal deflection spectroscopy (PDS), was used for layers grown on quartz substrates and is appealing from the point of view of sample fabrication. The second, a novel inverse modelling (IM) approach based on reflectance and transmittance measurements, was instead used for layers grown on textured c-Si wafer substrates to mimic symmetrical samples. Although the absorption coefficients obtained from these two techniques slightly differ due to the different used substrates, we could successfully measure weak FCA in our CSPCs layers. Using an in-house developed multi-optical regime simulator and comparing modelled reflectance and transmittance with measured counterparts from symmetrical samples, we confirmed that with increasing doping concentration FCA increases; and found that the absorption coefficients obtained from IM can now be used to perform optical simulations of these CSPCs in solar cells.
AB - The optical modelling for optimizing high-efficiency c-Si solar cells endowed with poly-SiOx or poly-SiCx carrier-selective passivating contacts (CSPCs) demands a thorough understanding of their optical properties, especially their absorption coefficient. Due to the mixed phase nature of these CSPCs, spectroscopic ellipsometry is unable to accurately detect the weak free carrier absorption (FCA) at long wavelengths. In this work, the absorption coefficient of doped poly-SiOx and poly-SiCx layers as function of oxygen and carbon content, respectively, was obtained for wavelengths (300–2000 nm) by means of two alternative techniques. The first approach, photothermal deflection spectroscopy (PDS), was used for layers grown on quartz substrates and is appealing from the point of view of sample fabrication. The second, a novel inverse modelling (IM) approach based on reflectance and transmittance measurements, was instead used for layers grown on textured c-Si wafer substrates to mimic symmetrical samples. Although the absorption coefficients obtained from these two techniques slightly differ due to the different used substrates, we could successfully measure weak FCA in our CSPCs layers. Using an in-house developed multi-optical regime simulator and comparing modelled reflectance and transmittance with measured counterparts from symmetrical samples, we confirmed that with increasing doping concentration FCA increases; and found that the absorption coefficients obtained from IM can now be used to perform optical simulations of these CSPCs in solar cells.
KW - Absorption coefficients
KW - Carrier-selective passivating contacts
KW - Photothermal deflection spectroscopy
KW - Poly-SiC
KW - Poly-SiO
KW - Reflection-transmission
UR - http://www.scopus.com/inward/record.url?scp=85082039242&partnerID=8YFLogxK
U2 - 10.1016/j.solmat.2020.110507
DO - 10.1016/j.solmat.2020.110507
M3 - Article
AN - SCOPUS:85082039242
SN - 0927-0248
VL - 210
JO - Solar Energy Materials and Solar Cells
JF - Solar Energy Materials and Solar Cells
M1 - 110507
ER -