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Title: Effect of silicon oxide thickness on polysilicon based passivated contacts for high-efficiency crystalline silicon solar cells

Abstract

In this paper, we have investigated the effect of SiOx thickness (1-3 nm) on the performance of polycrystalline (poly) Si/SiOx/monocrystalline Si (c-Si) passivated contacts. Our results show that for both n- and p-type contacts, there is an optimum SiOx thickness of 1.4-1.6 nm for obtaining the highest implied open-circuit voltage (i-Voc) values of ~739 and ~700 mV, respectively. For contacts with SiOx thicker than 1.6 nm, the i-Voc drops due to reduced field-effect passivation. We attribute this to the fact that a thicker SiOx layer hinders the diffusion of both n- and p-type dopants into the c-Si wafer resulting in a junction that is very close to the c-Si/SiOx interface, which increases carrier recombination most likely due to the presence of defects at this interface. The resistivity measured through the metal/poly-Si/SiOx/c-Si stack is independent of SiOx thickness up to 1.6 nm, and increases exponentially by several orders of magnitude with further increase in SiOx thickness due to inefficient tunneling transport. Finally, the extent of metallization-induced degradation of the poly-Si/SiOx/c-Si contacts is worst for the thinnest SiOx investigated (~1 nm), and interestingly it is not completely mitigated even for a ~3 nm thick SiOx.

Authors:
 [1];  [2];  [2];  [2];  [2];  [1];  [2]
  1. Colorado School of Mines, Golden, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
OSTI Identifier:
1461857
Alternate Identifier(s):
OSTI ID: 1548168
Report Number(s):
NREL/JA-5900-71510
Journal ID: ISSN 0927-0248
Grant/Contract Number:  
AC36-08GO28308; SETP DE-EE00030301
Resource Type:
Accepted Manuscript
Journal Name:
Solar Energy Materials and Solar Cells
Additional Journal Information:
Journal Volume: 185; Journal Issue: C; Journal ID: ISSN 0927-0248
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; silicon solar cell; passivated contact; passivation; silicon oxide; contact resistivity; metallization-induced degradation

Citation Formats

Kale, Abhijit S., Nemeth, William, Harvey, Steven P., Page, Matthew, Young, David L., Agarwal, Sumit, and Stradins, Paul. Effect of silicon oxide thickness on polysilicon based passivated contacts for high-efficiency crystalline silicon solar cells. United States: N. p., 2018. Web. https://doi.org/10.1016/j.solmat.2018.05.011.
Kale, Abhijit S., Nemeth, William, Harvey, Steven P., Page, Matthew, Young, David L., Agarwal, Sumit, & Stradins, Paul. Effect of silicon oxide thickness on polysilicon based passivated contacts for high-efficiency crystalline silicon solar cells. United States. https://doi.org/10.1016/j.solmat.2018.05.011
Kale, Abhijit S., Nemeth, William, Harvey, Steven P., Page, Matthew, Young, David L., Agarwal, Sumit, and Stradins, Paul. Tue . "Effect of silicon oxide thickness on polysilicon based passivated contacts for high-efficiency crystalline silicon solar cells". United States. https://doi.org/10.1016/j.solmat.2018.05.011. https://www.osti.gov/servlets/purl/1461857.
@article{osti_1461857,
title = {Effect of silicon oxide thickness on polysilicon based passivated contacts for high-efficiency crystalline silicon solar cells},
author = {Kale, Abhijit S. and Nemeth, William and Harvey, Steven P. and Page, Matthew and Young, David L. and Agarwal, Sumit and Stradins, Paul},
abstractNote = {In this paper, we have investigated the effect of SiOx thickness (1-3 nm) on the performance of polycrystalline (poly) Si/SiOx/monocrystalline Si (c-Si) passivated contacts. Our results show that for both n- and p-type contacts, there is an optimum SiOx thickness of 1.4-1.6 nm for obtaining the highest implied open-circuit voltage (i-Voc) values of ~739 and ~700 mV, respectively. For contacts with SiOx thicker than 1.6 nm, the i-Voc drops due to reduced field-effect passivation. We attribute this to the fact that a thicker SiOx layer hinders the diffusion of both n- and p-type dopants into the c-Si wafer resulting in a junction that is very close to the c-Si/SiOx interface, which increases carrier recombination most likely due to the presence of defects at this interface. The resistivity measured through the metal/poly-Si/SiOx/c-Si stack is independent of SiOx thickness up to 1.6 nm, and increases exponentially by several orders of magnitude with further increase in SiOx thickness due to inefficient tunneling transport. Finally, the extent of metallization-induced degradation of the poly-Si/SiOx/c-Si contacts is worst for the thinnest SiOx investigated (~1 nm), and interestingly it is not completely mitigated even for a ~3 nm thick SiOx.},
doi = {10.1016/j.solmat.2018.05.011},
journal = {Solar Energy Materials and Solar Cells},
number = C,
volume = 185,
place = {United States},
year = {2018},
month = {5}
}

Journal Article:

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Cited by: 11 works
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Figures / Tables:

Fig. 1 Fig. 1: Effect of thermally grown SiOx thickness on the i-Voc of symmetric n- (□) and p-type (red ○) passivated contact test structures shown in the inset. The i-Voc for n- (■) and p-type (red ●) passivated contacts with ~1.15 nm thick RCA SiOx is shown for comparison. The dashedmore » lines are a guide to the eye.« less

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    Works referencing / citing this record:

    Understanding the charge transport mechanisms through ultrathin SiO x layers in passivated contacts for high-efficiency silicon solar cells
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    • Kale, Abhijit S.; Nemeth, William; Guthrey, Harvey
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    • DOI: 10.1063/1.5081832

    Metal-induced gap states in passivating metal/silicon contacts
    journal, February 2019

    • Sajjad, Muhammad; Yang, Xinbo; Altermatt, Pietro
    • Applied Physics Letters, Vol. 114, Issue 7
    • DOI: 10.1063/1.5066423

      Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.