Damage free laser ablation of SiO{sub 2} for local contact opening on silicon solar cells using an a-Si:H buffer layer

Journal Article · Mon Feb 15 00:00:00 EST 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3309382· OSTI ID:21476143

Mangersnes, Krister; Foss, Sean Erik; Thoegersen, Annett ^[1]

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1. Institute for Energy Technology, Department of Solar Energy, Instituttveien 18, 2007 Kjeller (Norway)

We have used a Q-switched Nd:YVO{sub 4}, diode pumped 532 nm laser with nanosecond pulses, and a spot diameter of 40 {mu}m to ablate a layer of plasma enhanced chemical vapor deposited (PECVD) SiO{sub 2} on n-type Cz silicon, with the aim of making local contact openings on back-junction silicon solar cells. Laser pulses within the ns range are usually believed to be incompatible with processing of high efficiency solar cells because such long pulses induce too much damage into the underlying silicon lattice. This is due to thermal dissipation. In this work, a PECVD layer of a-Si:H between the n-type silicon and the dielectric layer is shown to absorb much of the laser radiation and allows for ablation at laser fluences lower than the ablation threshold of crystalline silicon. In addition, the a-Si:H layer serves as an excellent surface passivation layer for the silicon substrate. We show that it is possible to ablate PECVD SiO{sub 2} in a damage free way with fluences five times lower than those needed to ablate crystalline Si. Our results are verified experimentally with high resolution transmission electron microscopy of the crystal structure in the laser irradiated areas, and quasi-steady-state photoconductance measurements of emitter saturation currents. In addition, we have simulated the energy transfer from a ns 532 nm Gaussian shaped laser beam to a SiO{sub 2} covered Si lattice with and without the a-Si:H buffer layer. A model that coincides very well with the experiments is found.

• OSTI ID: 21476143
• Journal Information: Journal of Applied Physics, Vol. 107, Issue 4; Other Information: DOI: 10.1063/1.3309382; (c) 2010 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABLATION
CHEMICAL VAPOR DEPOSITION
CRYSTAL STRUCTURE
DIELECTRIC MATERIALS
HYDROGEN
LASER RADIATION
LAYERS
NEODYMIUM LASERS
PHOTOCONDUCTIVITY
PLASMA
Q-SWITCHING
SEMICONDUCTOR MATERIALS
SILICON
SILICON OXIDES
SILICON SOLAR CELLS
SUBSTRATES
SURFACES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
CHALCOGENIDES
CHEMICAL COATING
DEPOSITION
DIRECT ENERGY CONVERTERS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
ELEMENTS
EQUIPMENT
FILMS
LASERS
MATERIALS
MICROSCOPY
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PHYSICAL PROPERTIES
RADIATIONS
SEMIMETALS
SILICON COMPOUNDS
SOLAR CELLS
SOLAR EQUIPMENT
SOLID STATE LASERS
SURFACE COATING