Shallow junction photovoltaic devices

a photovoltaic device and shallow junction technology, applied in the direction of sustainable manufacturing/processing, semiconductor devices, climate sustainability, etc., can solve the problems of limiting the vsub>oc /sub>due, and difficult to form a high doping concentration, so as to reduce the recombination of augers

Inactive Publication Date: 2015-09-10
GLOBALFOUNDRIES INC
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  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent describes a method for making a photovoltaic device by growing layers of doakhcptically reduced silicon with specific doping concentrations, dislocation densities, and hydrogen content to reduce Auger recombination. The device also includes conductive electrodes and a passivation layer to improve its performance. The technical effects of this method include reducing recombination and improving the device's efficiency.

Problems solved by technology

In addition, doping levels below 1019 cm−3 do not completely shield the carriers from the substrate surface, therefore limiting the Voc due to recombination at localized metal contact areas.
It is very difficult to form a high doping concentration especially in thin layers by conventional diffusion.

Method used

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  • Shallow junction photovoltaic devices

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Embodiment Construction

[0029]In accordance with the present principles, photovoltaic devices are provided having junctions formed that are thin (preferably less than about 5 nm), highly doped (preferably greater than 1019 cm−3) epitaxial (epi) layers with very low dislocation density (e.g., less than 105 cm−2) resulting in shallow junctions essentially having a depth equal to that of the epitaxial layer thickness. The very thin epitaxial layers result in low Auger recombination levels and have little or no impact on photovoltaic cell performance. In addition, due to the high doping concentration in the epi layer(s), a density of minority carriers reaching a substrate surface is reduced, and therefore a modest surface passivation is sufficient to achieve sufficiently low surface recombination levels. The thin epitaxial layers also permit short growth times, which is desirable for high manufacturing throughput.

[0030]In one embodiment, an interdigitated back-contact (IBC) photovoltaic device includes junctio...

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Abstract

A method for fabricating a photovoltaic device includes forming a first contact on a crystalline substrate, by epitaxially growing a first doped layer having a doping concentration of 1019 cm−3 or greater, a dislocation density of 105 cm−2 or smaller, a hydrogen content of 0.1 atomic percent or smaller, and a thickness configured to reduce Auger recombination in the epitaxially grown doped layer. A first passivation layer is formed on the first doped layer. A second contact is formed on the crystalline substrate on a side opposite the first contact by epitaxially growing a second doped layer having a doping concentration of 1019 cm−3 or greater, a dislocation density of 105 cm−2 or smaller, a hydrogen content of 0.1 atomic percent or smaller and a thickness configured to reduce Auger recombination in the second epitaxially grown doped layer. A second passivation layer is formed on the second doped layer.

Description

RELATED APPLICATION DATA[0001]This application is a Continuation application of co-pending U.S. patent application Ser. No. 14 / 055,273 filed on Oct. 16, 2013, incorporated herein by reference in its entirety, which is a Continuation application of co-pending U.S. patent application Ser. No. 14 / 025,525 filed on Sep. 12, 2013, incorporated herein by reference in its entirety.BACKGROUND[0002]1. Technical Field[0003]The present invention relates to photovoltaic devices, and more particularly to devices and methods with passivated shallow junctions to reduce Auger recombination effects.[0004]2. Description of the Related Art[0005]In conventional front-contact solar cells, junctions are formed by diffusion and typically are a few hundreds of nanometers but less than 1 micron deep. Although higher doping levels are desired for increasing the splitting of quasi-Fermi levels and thus improving an open circuit voltage of the solar cell, the doping levels are chosen below 1019 cm−3 (typically ...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): H01L31/0224H01L31/0216H01L31/0392
CPCH01L31/022466H01L31/02167H01L31/0392H01L31/068H01L31/0682H01L31/1804Y02E10/547H01L31/022441Y02P70/50H01L31/18
InventorCHAN, KEVIN K.HEKMATSHOARTABARI, BAHMANNING, TAK H.
OwnerGLOBALFOUNDRIES INC