TY - JOUR

T1 - Temperature-dependent contact resistance of carrier selective Poly-Si on oxide junctions

AU - Folchert, Nils

AU - Rienäcker, Michael

AU - Yeo, A. A.

AU - Min, Byungsul

AU - Peibst, Robby

AU - Brendel, Rolf

N1 - Funding Information: We thank Guido Glowatzki, Heike Kohlenberger and Sabine Schmidt for their help with sample processing and Manuel Stratmann for the analysis of pinhole densities. We gratefully thank Tobias Wietler (ISFH) and Prof. Uwe Rau (FZ Jülich) for helpful discussions and hints. This work was supported by the Ministry for Science and Culture of lower Saxony in the framework of the project vOx and has also received funding from the European Union 's Horizon 2020 research and innovation program under grant agreement No 727529 (DISC). Publisher Copyright: © 2018 Elsevier B.V. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.

PY - 2018/10

Y1 - 2018/10

N2 - Carrier selective junctions using a poly-silicon/ silicon oxide stack on crystalline silicon feature low recombination currents J0 whilst allowing for low contact resistivity ρC. We describe the limiting current transport mechanism as a combination of homogeneous tunneling through the interfacial silicon oxide layer and transport through pinholes where the interfacial silicon oxide layer is locally disrupted. We present an experimental method and its theoretical basis to discriminate between homogenous tunneling and local pinhole transport mechanisms on n + /n or p + /p junctions by measuring the temperature-dependent contact resistance. Theory predicts opposing trends for the temperature dependencies of tunneling and pinhole transport. This allows identifying the dominant transport path. For the contact resistance of two differently prepared poly-Si/ silicon oxide/ c-Si junctions we either find clear pinhole-type or clear tunneling-type temperature dependence. Pinhole transport contributes more than 94% to the total current for the sample with a 2.1 nm-thick interfacial silicon oxide that we anneal at a temperature of 1050 °C to achieve highest selectivity. In contrast pinhole transport contributes less than 35 % to the total current for the sample with a 1.7 nm-thick silicon oxide that we annealed at only 700 °C in order to avoid pinholes.

AB - Carrier selective junctions using a poly-silicon/ silicon oxide stack on crystalline silicon feature low recombination currents J0 whilst allowing for low contact resistivity ρC. We describe the limiting current transport mechanism as a combination of homogeneous tunneling through the interfacial silicon oxide layer and transport through pinholes where the interfacial silicon oxide layer is locally disrupted. We present an experimental method and its theoretical basis to discriminate between homogenous tunneling and local pinhole transport mechanisms on n + /n or p + /p junctions by measuring the temperature-dependent contact resistance. Theory predicts opposing trends for the temperature dependencies of tunneling and pinhole transport. This allows identifying the dominant transport path. For the contact resistance of two differently prepared poly-Si/ silicon oxide/ c-Si junctions we either find clear pinhole-type or clear tunneling-type temperature dependence. Pinhole transport contributes more than 94% to the total current for the sample with a 2.1 nm-thick interfacial silicon oxide that we anneal at a temperature of 1050 °C to achieve highest selectivity. In contrast pinhole transport contributes less than 35 % to the total current for the sample with a 1.7 nm-thick silicon oxide that we annealed at only 700 °C in order to avoid pinholes.

KW - Contact resistance

KW - Passivating contacts

KW - Pinhole transport

KW - POLO

KW - Poly-Si

KW - Selective contacts

KW - Transfer-length-method

KW - Tunneling

UR - http://www.scopus.com/inward/record.url?scp=85048153586&partnerID=8YFLogxK

U2 - 10.1016/j.solmat.2018.05.046

DO - 10.1016/j.solmat.2018.05.046

M3 - Article

AN - SCOPUS:85048153586

VL - 185

SP - 425

EP - 430

JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

SN - 0927-0248

ER -