Electrical scanning probe microscopy approaches to investigate solar cell junctions and devices

J. Alvarez; C. Marchat; A. Morisset; L. Dai; J.-P. Kleider; Raphaël Cabal; P. R. i Cabarrocas

doi:10.1117/12.2540422

31 January 2020 Electrical scanning probe microscopy approaches to investigate solar cell junctions and devices

J. Alvarez, C. Marchat, A. Morisset, L. Dai, J.-P. Kleider, Raphaël Cabal, P. R. i Cabarrocas

Proceedings Volume 11288, Quantum Sensing and Nano Electronics and Photonics XVII; 112880U (2020) https://doi.org/10.1117/12.2540422
Event: SPIE OPTO, 2020, San Francisco, California, United States

Abstract

C-AFM and KPFM techniques have been applied to investigate advanced junctions that are currently involved in highly efficient silicon solar cells. Our first study focuses on silicon heterojunctions and notably hydrogenated amorphous silicon (a-Si:H)/crystalline silicon (c-Si) P/n or N/p heterostructures which band bending at the interface forms a 2D channel. This conductive channel was indeed evidenced for the first time by cross-sectional investigations by C-AFM confirming the analysis of macroscopic planar conductance measurements. A second example of nanoscale characterization concerns the passivating selective contacts consisting in a thin silicon oxide (SiOx) layer between the c-Si and a highly doped polysilicon (poly-Si) layer. The electrical carrier transport is here not limited by the oxide layer and it is assumed that tunnelling through the oxide and/or the presence of pinholes are the main competitive mechanisms. For this specific heterostructure KPFM reveals local surface potential drops of 15- 30 mV, which do not exist on samples without SiOx. These potential drops suggest the presence of pinholes that are formed during the poly-Si annealing process performed in the range of 700-900°C. Finally, in a third study, we concentrate on p-i-n radial junction (RJ) silicon nanowire (SiNW) devices that are investigated under illumination by KPFM, in the so-called surface photovoltage (SPV) technique. This work focuses on the possibility of extracting the open-circuit voltage (VOC) on single isolated SiNW RJ by local SPV measurements using different AFM tip shapes and illumination directions in order to minimize shadowing effects.

Conference Presentation

Citation Download Citation

J. Alvarez, C. Marchat, A. Morisset, L. Dai, J.-P. Kleider, Raphaël Cabal, and P. R. i Cabarrocas "Electrical scanning probe microscopy approaches to investigate solar cell junctions and devices", Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 112880U (31 January 2020); https://doi.org/10.1117/12.2540422

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