Details
| Original language | English |
|---|---|
| Pages (from-to) | 509-514 |
| Number of pages | 6 |
| Journal | Progress in Photovoltaics: Research and Applications |
| Volume | 25 |
| Issue number | 7 |
| Early online date | 11 Aug 2016 |
| Publication status | Published - Jul 2017 |
Abstract
Passivated Emitter and Rear Cells (PERC) are currently being introduced into mass production. The conversion efficiency of industrial p-type PERC cells is limited by the emitter saturation current density of around 90 fA/cm2 of conventional homogeneously POCl3 diffused emitters. In this paper we investigate two alternative emitter formation technologies. The first approach named in-situ oxidation inserts a short thermal oxidation in-between the phosphorus silicate glass deposition and the drive-in of a conventional homogeneous POCl3 diffusion thereby reducing the phosphorus surface concentration. The second approach named Gas Phase Etch Back (GEB) selectively removes around 40 nm of the highly doped surface of the POCl3 diffused emitter by the reactive gas phase of the wet chemical rear polishing bath. Whereas the conventional POCl3 emitter exhibits a phosphorus surface doping concentration of 3 × 1020 cm−3, the in-situ oxidation and the GEB process reduce the doping concentration to 7 × 1019 cm−3 and 4 × 1019 cm−3, respectively. Accordingly, the emitter saturation current density is reduced to excellent values of 22 fA/cm2 (in-situ oxidation) and 28 fA/cm2 (GEB) compared with 89 fA/cm2 for the reference POCl3 diffusion. Whereas the reference POCl3 emitter limits the PERC conversion efficiency η to 21.1% and the open circuit voltage Voc to 655 mV, the in-situ oxidation improves the PERC current–voltage parameters up to 21.3% and 663 mV. The highest efficiency of 21.6% is obtained with the selective GEB emitter. When solving series resistance issues with the most advanced GEB emitter, the measured Voc and Jsc values would support PERC conversion efficiencies up to 21.9%.
Keywords
- emitter, gas phase etch back, in-situ oxidation, PERC, phosphorus doping, silicon solar cells
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Energy(all)
- Renewable Energy, Sustainability and the Environment
- Physics and Astronomy(all)
- Condensed Matter Physics
- Engineering(all)
- Electrical and Electronic Engineering
Sustainable Development Goals
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In: Progress in Photovoltaics: Research and Applications, Vol. 25, No. 7, 07.2017, p. 509-514.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Emitter saturation current densities of 22 fA/cm2 applied to industrial PERC solar cells approaching 22% conversion efficiency
AU - Dullweber, Thorsten
AU - Hannebauer, Helge
AU - Dorn, Silke
AU - Schimanke, Sabrina
AU - Merkle, Agnes
AU - Hampe, Carsten
AU - Brendel, Rolf
N1 - Publisher Copyright: Copyright © 2016 John Wiley & Sons, Ltd. Copyright: Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/7
Y1 - 2017/7
N2 - Passivated Emitter and Rear Cells (PERC) are currently being introduced into mass production. The conversion efficiency of industrial p-type PERC cells is limited by the emitter saturation current density of around 90 fA/cm2 of conventional homogeneously POCl3 diffused emitters. In this paper we investigate two alternative emitter formation technologies. The first approach named in-situ oxidation inserts a short thermal oxidation in-between the phosphorus silicate glass deposition and the drive-in of a conventional homogeneous POCl3 diffusion thereby reducing the phosphorus surface concentration. The second approach named Gas Phase Etch Back (GEB) selectively removes around 40 nm of the highly doped surface of the POCl3 diffused emitter by the reactive gas phase of the wet chemical rear polishing bath. Whereas the conventional POCl3 emitter exhibits a phosphorus surface doping concentration of 3 × 1020 cm−3, the in-situ oxidation and the GEB process reduce the doping concentration to 7 × 1019 cm−3 and 4 × 1019 cm−3, respectively. Accordingly, the emitter saturation current density is reduced to excellent values of 22 fA/cm2 (in-situ oxidation) and 28 fA/cm2 (GEB) compared with 89 fA/cm2 for the reference POCl3 diffusion. Whereas the reference POCl3 emitter limits the PERC conversion efficiency η to 21.1% and the open circuit voltage Voc to 655 mV, the in-situ oxidation improves the PERC current–voltage parameters up to 21.3% and 663 mV. The highest efficiency of 21.6% is obtained with the selective GEB emitter. When solving series resistance issues with the most advanced GEB emitter, the measured Voc and Jsc values would support PERC conversion efficiencies up to 21.9%.
AB - Passivated Emitter and Rear Cells (PERC) are currently being introduced into mass production. The conversion efficiency of industrial p-type PERC cells is limited by the emitter saturation current density of around 90 fA/cm2 of conventional homogeneously POCl3 diffused emitters. In this paper we investigate two alternative emitter formation technologies. The first approach named in-situ oxidation inserts a short thermal oxidation in-between the phosphorus silicate glass deposition and the drive-in of a conventional homogeneous POCl3 diffusion thereby reducing the phosphorus surface concentration. The second approach named Gas Phase Etch Back (GEB) selectively removes around 40 nm of the highly doped surface of the POCl3 diffused emitter by the reactive gas phase of the wet chemical rear polishing bath. Whereas the conventional POCl3 emitter exhibits a phosphorus surface doping concentration of 3 × 1020 cm−3, the in-situ oxidation and the GEB process reduce the doping concentration to 7 × 1019 cm−3 and 4 × 1019 cm−3, respectively. Accordingly, the emitter saturation current density is reduced to excellent values of 22 fA/cm2 (in-situ oxidation) and 28 fA/cm2 (GEB) compared with 89 fA/cm2 for the reference POCl3 diffusion. Whereas the reference POCl3 emitter limits the PERC conversion efficiency η to 21.1% and the open circuit voltage Voc to 655 mV, the in-situ oxidation improves the PERC current–voltage parameters up to 21.3% and 663 mV. The highest efficiency of 21.6% is obtained with the selective GEB emitter. When solving series resistance issues with the most advanced GEB emitter, the measured Voc and Jsc values would support PERC conversion efficiencies up to 21.9%.
KW - emitter
KW - gas phase etch back
KW - in-situ oxidation
KW - PERC
KW - phosphorus doping
KW - silicon solar cells
UR - http://www.scopus.com/inward/record.url?scp=84981555994&partnerID=8YFLogxK
U2 - 10.1002/pip.2806
DO - 10.1002/pip.2806
M3 - Article
AN - SCOPUS:84981555994
VL - 25
SP - 509
EP - 514
JO - Progress in Photovoltaics: Research and Applications
JF - Progress in Photovoltaics: Research and Applications
SN - 1062-7995
IS - 7
ER -