Material combination of Tunnel-SiO2 with a (sub-)Monolayer of ALD-AlOx on silicon offering a highly passivating hole selective contact

Daniel Hiller; Philipp Hoenicke; Dirk König

doi:10.1016/j.solmat.2020.110654

Material combination of Tunnel-SiO₂ with a (sub-)Monolayer of ALD-AlO_x on silicon offering a highly passivating hole selective contact

Daniel Hiller^*, Philipp Hoenicke, Dirk König^*

^*Corresponding author for this work

The Australian National University

Research output: Contribution to journal › Article › peer-review

25 Citations (Scopus)

Abstract

In this work, we investigate a passivating hole-selective tunnel contact on crystalline silicon (Si) based on an ultrathin thermal SiO₂ and a (sub-)monolayer thick aluminum oxide (AlO_x) deposited by atomic layer deposition (ALD) with 1 to 7 cycles. Rapid thermal annealing (RTA) is essential to activate the passivation and intense visible light is demonstrated to play a key role in the formation and occupation of the Al-induced acceptor states in SiO₂ that provide the passivation. This simple stack provides very good surface passivation on n-type Si with a surface saturation current density as low as J_0s = 25 fA/cm² (S_eff = 2.7 cm/s) and a contact resistivity ρ_c of ~200 mΩ cm², while being Si-dopant-free, fully transparent and firing-stable. The Al-deposition on thermal SiO₂ during the initial ALD-cycles is studied carefully by synchrotron-based reference-free grazing incidence X-ray fluorescence spectrometry (GIXRF). Different metallization and capping approaches are tested and discussed.

Original language	English
Article number	110654
Number of pages	8
Journal	Solar Energy Materials and Solar Cells
Volume	215
Early online date	19 Jun 2020
DOIs	https://doi.org/10.1016/j.solmat.2020.110654
Publication status	Published - 15 Sept 2020

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title = "Material combination of Tunnel-SiO2 with a (sub-)Monolayer of ALD-AlOx on silicon offering a highly passivating hole selective contact",

abstract = "In this work, we investigate a passivating hole-selective tunnel contact on crystalline silicon (Si) based on an ultrathin thermal SiO2 and a (sub-)monolayer thick aluminum oxide (AlOx) deposited by atomic layer deposition (ALD) with 1 to 7 cycles. Rapid thermal annealing (RTA) is essential to activate the passivation and intense visible light is demonstrated to play a key role in the formation and occupation of the Al-induced acceptor states in SiO2 that provide the passivation. This simple stack provides very good surface passivation on n-type Si with a surface saturation current density as low as J0s = 25 fA/cm2 (Seff = 2.7 cm/s) and a contact resistivity ρc of ~200 mΩ cm2, while being Si-dopant-free, fully transparent and firing-stable. The Al-deposition on thermal SiO2 during the initial ALD-cycles is studied carefully by synchrotron-based reference-free grazing incidence X-ray fluorescence spectrometry (GIXRF). Different metallization and capping approaches are tested and discussed.",

keywords = "Aluminum oxide, Atomic layer deposition, Grazing incidence X-ray fluorescence spectrometry, Hole-selective contact, Monolayer, Silicon surface passivation",

author = "Daniel Hiller and Philipp Hoenicke and Dirk K{\"o}nig",

note = "Publisher Copyright: {\textcopyright} 2020",

year = "2020",

month = sep,

day = "15",

doi = "10.1016/j.solmat.2020.110654",

language = "English",

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AU - Hiller, Daniel

AU - Hoenicke, Philipp

AU - König, Dirk

PY - 2020/9/15

Y1 - 2020/9/15

N2 - In this work, we investigate a passivating hole-selective tunnel contact on crystalline silicon (Si) based on an ultrathin thermal SiO2 and a (sub-)monolayer thick aluminum oxide (AlOx) deposited by atomic layer deposition (ALD) with 1 to 7 cycles. Rapid thermal annealing (RTA) is essential to activate the passivation and intense visible light is demonstrated to play a key role in the formation and occupation of the Al-induced acceptor states in SiO2 that provide the passivation. This simple stack provides very good surface passivation on n-type Si with a surface saturation current density as low as J0s = 25 fA/cm2 (Seff = 2.7 cm/s) and a contact resistivity ρc of ~200 mΩ cm2, while being Si-dopant-free, fully transparent and firing-stable. The Al-deposition on thermal SiO2 during the initial ALD-cycles is studied carefully by synchrotron-based reference-free grazing incidence X-ray fluorescence spectrometry (GIXRF). Different metallization and capping approaches are tested and discussed.

AB - In this work, we investigate a passivating hole-selective tunnel contact on crystalline silicon (Si) based on an ultrathin thermal SiO2 and a (sub-)monolayer thick aluminum oxide (AlOx) deposited by atomic layer deposition (ALD) with 1 to 7 cycles. Rapid thermal annealing (RTA) is essential to activate the passivation and intense visible light is demonstrated to play a key role in the formation and occupation of the Al-induced acceptor states in SiO2 that provide the passivation. This simple stack provides very good surface passivation on n-type Si with a surface saturation current density as low as J0s = 25 fA/cm2 (Seff = 2.7 cm/s) and a contact resistivity ρc of ~200 mΩ cm2, while being Si-dopant-free, fully transparent and firing-stable. The Al-deposition on thermal SiO2 during the initial ALD-cycles is studied carefully by synchrotron-based reference-free grazing incidence X-ray fluorescence spectrometry (GIXRF). Different metallization and capping approaches are tested and discussed.

KW - Aluminum oxide

KW - Atomic layer deposition

KW - Grazing incidence X-ray fluorescence spectrometry

KW - Hole-selective contact

KW - Monolayer

KW - Silicon surface passivation

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DO - 10.1016/j.solmat.2020.110654

M3 - Article

SN - 0927-0248

VL - 215

JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

M1 - 110654

ER -

Material combination of Tunnel-SiO₂ with a (sub-)Monolayer of ALD-AlO_x on silicon offering a highly passivating hole selective contact

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