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Title: Explicit analytical modeling of the low frequency a-Si:H/c-Si heterojunction capacitance: Analysis and application to silicon heterojunction solar cells

We develop a fully analytical model in order to describe the temperature dependence of the low frequency capacitance of heterojunctions between hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si). We demonstrate that the slope of the capacitance-temperature (C-T) curve is strongly enhanced if the c-Si surface is under strong inversion conditions compared to the usually assumed depletion layer capacitance. We have extended our analytical model to integrate a very thin undoped (i) a-Si:H layer at the interface and the finite thickness of the doped a-Si:H layer that are used in high efficiency solar cells for the passivation of interface defects and to limit short circuit current losses. Finally, using our calculations, we analyze experimental data on high efficiency silicon heterojunction solar cells. The transition from the strong inversion limited behavior to the depletion layer behavior is discussed in terms of band offsets, density of states in a-Si:H, and work function of the indium tin oxide (ITO) front electrode. In particular, it is evidenced that strong inversion conditions prevail at the c-Si surface at high temperatures down to 250 K, which can only be reproduced if the ITO work function is larger than 4.7 eV.
Authors:
 [1] ;  [2] ; ; ; ;  [3]
  1. Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, Miusskaya sq., 4, Moscow 125047 (Russian Federation)
  2. (Group of electrical engineering of Paris), CNRS UMR 8507, CentraleSupélec, Univ Paris-Sud, Sorbonne Universités-UPMC Univ Paris 06, 11 rue Joliot-Curie, Plateau de Moulon, F-91192 Gif-sur-Yvette Cedex (France)
  3. GeePs (Group of electrical engineering of Paris), CNRS UMR 8507, CentraleSupélec, Univ Paris-Sud, Sorbonne Universités-UPMC Univ Paris 06, 11 rue Joliot-Curie, Plateau de Moulon, F-91192 Gif-sur-Yvette Cedex (France)
Publication Date:
OSTI Identifier:
22489502
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 11; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CAPACITANCE; CURRENTS; DENSITY OF STATES; DEPLETION LAYER; DOPED MATERIALS; ELECTRICAL FAULTS; ELECTRODES; HETEROJUNCTIONS; INDIUM; PASSIVATION; SILICON; SOLAR CELLS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; TIN OXIDES; WORK FUNCTIONS