Evaluating the impact of thermal annealing on <i>c</i>-Si/Al2O3 interface: Correlating electronic properties to infrared absorption

Lee, Chang‐Yeh; Deng, Shaoren; Zhang, T.; Cui, Xin; Khoo, Kean Thong; Kim, K.; Hoex, Bram

doi:10.1063/1.5036738

Cited by 11 publications

(5 citation statements)

References 39 publications

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“…One can also notice that the shift of the C-V characteristic to the right, suggesting a decrease of positive charges or the introduction of extra negative charges. A similar shift was observed for Al 2 O 3 /Si under thermal treatment [44] and could be explained by the release of the hydroxyl group. Unfortunately, information regarding the composition and impurities of the films after annealing is not available.…”

Section: Resultssupporting

confidence: 79%

Influence of substrate biasing on structural, chemical and electrical properties of Al₂O₃ thin films deposited by PEALD

Boubenia¹,

Gauthier²,

Legallais³

et al. 2022

Semicond. Sci. Technol.

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High-k materials are needed to minimise the gate leakage current in high-speed and high-power switching applications. In this regard, aluminium oxide (Al2O3) deposited by Plasma Enhanced Atomic Layer Deposition (PEALD) is gaining extensive attention to be used as high-k material in microelectronics. In this work, we studied the effect of substrate biasing during the oxidizing plasma step on physical, chemical and electrical properties of Al2O3 thin films grown by PEALD on silicon substrate. We show that the structural and electrical properties such as the flat band voltage, and chemical composition can be tuned with the applied substrate bias. Indeed, we highlight that the dielectric constant of the MIS capacitor decreases from 8.5 to 6.5 and the charge polarity of the film is modulated from negative to positive when the applied substrate bias is increased. Using morphological and structural characterisations, we show that the substrate bias significantly affects the chemical composition of Al2O3 thin film layer. Moreover, we highlight by cross-sectional transmission electron the presence of an interfacial layer between Si and Al2O3 which could significantly influence the electrical properties of the deposited thin film. The chemical composition of this interfacial layer can be controlled by the applied substrate bias. Using a series of Energy Dispersive X-ray (EDX) experiments, we further confirm the formation of aluminosilicate under low substrate bias condition while silicon oxide is formed under high bias. These findings show that the substrate biasing plays a critical role in defining physical, chemical as well as electrical properties of the PEALD Al2O3 thin films.

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Section: Resultssupporting

confidence: 79%

Influence of substrate biasing on structural, chemical and electrical properties of Al₂O₃ thin films deposited by PEALD

Boubenia¹,

Gauthier²,

Legallais³

et al. 2022

Semicond. Sci. Technol.

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“…Small Si–O peaks centered at ∼103.3 eV were also observed as shown in Figure S2, which confirms the existence of an SiO X layer despite the fact that this interlayer was not visible at the c -Si( p )/MoO X interface in the high-resolution transmission electron microscope (HRTEM) image in Figure a. The oxygen atoms in the SiO X likely originated from the O 3 exposure during the ALD process or from O migration from the MoO X layer at the interface.…”

Section: Results and Discussionsupporting

confidence: 56%

Bilayer MoO_X/CrO_X Passivating Contact Targeting Highly Stable Silicon Heterojunction Solar Cells

Pan

Wang

et al. 2020

ACS Appl. Mater. Interfaces

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Molybdenum oxide (MoO X , X < 3) has been successfully demonstrated as an efficient passivating hole-selective contact in crystalline Si (c-Si) heterojunction solar cells because of its large bandgap (∼3.2 eV) and work function (∼6.9 eV). However, the severe performance degradation coming from the instability of the MoO X and its interfaces has not been well addressed. In this work, we started with a c-Si(p)/MoO X heterojunction solar cell that yielded a power conversion efficiency (PCE) of 15.86%, in which the MoO X film was synthesized by industry-compatible atomic layer deposition (ALD). The initial PCE dropped to 10.20% after 2 days because of severe migration of O and Ag at the MoO X /Ag interface. We solved this by the insertion of a CrO X layer between the MoO X layer and the Ag electrode. The solar cell was found to be stable for more than 8 months in air because of the suppression of interface degradation. Our work demonstrates an effective way of improving the stability of silicon solar cells with transition metal oxide carrier selective contacts.

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“…With extra annealing treatment, both ALD processes show lower D it ≤ 1×10 11 cm -2 [24][25] . Regarding the eld-effect passivation, the thermal ALD-based Al 2 O 3 lm exhibits especially low Q it of the order of 10 11 cm -2 before annealing comparing to plasma ALD with Q it of the order of 10 12 cm -2 .…”

Section: Resultsmentioning

confidence: 98%

Simulation of a Charged Al2O3 Film as an Assisting Passivation Layer for a-Si Passivated Contact P-Type Silicon Solar Cells

Shen

Tang

2021

Silicon

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In this paper, a charged Al 2 O 3 tunneling lm as an assisting for amorphous Si (a-Si) passivated contact layer is proposed and theoretically simulated for its potential application in improving a-Si passivated contact p-type (a-PC-p) solar cell. The concept is based on an Ag/n + c-Si/p c-Si/Al 2 O 3 /p + a-Si/Al structure.The key feature is the introduction of a charged Al 2 O 3 layer, which facilitates the tunneling of holes through an Al 2 O 3 insulator layer accompanied by the reduction of interface defect density (D it ). The negative charge in the Al 2 O 3 layer makes the energy band of p-type c-Si bend upward, realizing the accumulation of holes and repelling of electrons at the c-Si/a-Si interface simultaneously. The in uence of interface negative charges (Q it ) between a-Si and c-Si, Al 2 O 3 thickness, Al 2 O 3 bandgap, interface defect density (D it ) at the a-Si/c-Si interface are systematically investigated on the output parameters of a-PC-p cells. Inserting a charged Al 2 O 3 lm between the c-Si/a-Si interface, a +4.2 % relative e ciency gain is predicted theoretically compared with the a-PC-p cells without the Al 2 O 3 layer. Subsequently, the device performance under various temperatures is simulated, and the insertion of a charged Al 2 O 3 layer obviously decreases the P max temperature coe cient from -0.336 % /℃ to -0.247 % /℃, which is analogous to that of Heterojunction with Intrinsic Thin layer (HIT) solar cell. The above results demonstrate a better temperature response for a-PC-p cells with a charged Al 2 O 3 layer, paving a road for its potential application in high-e ciency and high thermal stability a-PC-p solar cells. Highlights A charged Al 2 O 3 assisting passivation layer is proposed for a-Si PC-p The Al 2 O 3 layer makes the selective carrier tunneling at the c-Si/a-Si interface. A +4.2 % relative e ciency gain is predicted theoretically by the Al 2 O 3The insertion of the Al 2 O 3 layer reduces the P max temperature coe cient greatly.

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Evaluating the impact of thermal annealing on c-Si/Al2O3 interface: Correlating electronic properties to infrared absorption

Cited by 11 publications

References 39 publications

Influence of substrate biasing on structural, chemical and electrical properties of Al₂O₃ thin films deposited by PEALD

Influence of substrate biasing on structural, chemical and electrical properties of Al₂O₃ thin films deposited by PEALD

Bilayer MoO_X/CrO_X Passivating Contact Targeting Highly Stable Silicon Heterojunction Solar Cells

Simulation of a Charged Al2O3 Film as an Assisting Passivation Layer for a-Si Passivated Contact P-Type Silicon Solar Cells

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Evaluating the impact of thermal annealing on c-Si/Al2O3 interface: Correlating electronic properties to infrared absorption

Cited by 11 publications

References 39 publications

Influence of substrate biasing on structural, chemical and electrical properties of Al2O3 thin films deposited by PEALD

Influence of substrate biasing on structural, chemical and electrical properties of Al2O3 thin films deposited by PEALD

Bilayer MoOX/CrOX Passivating Contact Targeting Highly Stable Silicon Heterojunction Solar Cells

Simulation of a Charged Al2O3 Film as an Assisting Passivation Layer for a-Si Passivated Contact P-Type Silicon Solar Cells

Contact Info

Product

Resources

About

Influence of substrate biasing on structural, chemical and electrical properties of Al₂O₃ thin films deposited by PEALD

Influence of substrate biasing on structural, chemical and electrical properties of Al₂O₃ thin films deposited by PEALD

Bilayer MoO_X/CrO_X Passivating Contact Targeting Highly Stable Silicon Heterojunction Solar Cells