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Thermal oxidation for crystalline silicon solar cells exceeding 19% efficiency applying industrially feasible process technology
Author(s) -
Schultz Oliver,
Mette Ansgar,
Hermle Martin,
Glunz Stefan W.
Publication year - 2008
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.814
Subject(s) - passivation , materials science , monocrystalline silicon , silicon , thermal oxidation , crystalline silicon , oxide , aluminium , annealing (glass) , energy conversion efficiency , thermal , solar cell , chemical engineering , optoelectronics , metallurgy , layer (electronics) , nanotechnology , physics , meteorology , engineering
Thermal oxides are commonly used for the surface passivation of high‐efficiency silicon solar cells from mono‐ and multicrystalline silicon and have led to the highest conversion efficiencies reported so far. In order to improve the cost‐effectiveness of the oxidation process, a wet oxidation in steam ambience is applied and experimentally compared to a standard dry oxidation. The processes yield identical physical properties of the oxide. The front contact is created using a screen‐printing process of a hotmelt silver paste in combination with light‐induced silver plating. The contact formation on the front requires a short high‐temperature firing process, therefore the thermal stability of the rear surface passivation is very important. The surface recombination velocity of the fired oxide is experimentally determined to be below S ≤ 38 cm/s after annealing with a thin layer of evaporated aluminium on top. Monocrystalline solar cells are produced and 19·3% efficiency is obtained as best value on 4 cm 2 cell area. Simulations show the potential of the developed process to approach 20% efficiency. Copyright © 2008 John Wiley & Sons, Ltd.