Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate

Yehua Tang; Yuchao Wang; Chunlan Zhou; Ke-Fan Wang

doi:10.1088/1674-4926/24030032

J. Semicond. > 2024, Volume 45 > Issue 10 > 102302

ARTICLES

Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate

Yehua Tang^{1, §}, Yuchao Wang^{2, 3, §}, Chunlan Zhou^{3, 4,} and Ke-Fan Wang^5,

+ Author Affiliations

1. Electrical and Energy Engineering Department, Nantong Institute of Technology, Nantong 226000, China
2. Ningxia Research Center of Silicon Target and Silicon-Carbon Negative Materials Engineering Technology, School of Materials Science and Engineering, North Minzu University, Yinchuan 750021, China
3. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100049, China
4. School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
5. Henan Key Laboratory of Quantum Materials and Quantum Energy, School of Future Technology, Henan University, Kaifeng 475004, China
^§These authors contributed equally to this work.

Author Bio:

Yehua Tang was born in China, in 1982. She received the bachelor’s degree from Yunnan Normal University, Yunnan, China, in 2004, and the Ph.D. degree from the Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China, in 2013. From 2013 to 2019, she was a R & D director with the Eoplly New Energy Technology Co., Ltd., Nantong, Jiangsu, China. From 2019 to 2023, she has been an associated professor with the Henan University. Since 2023, she has been a Professor with Electrical and Energy Engineering Department, Nantong Institute of Technology, focusing on production technology of n-Si solar cells.

Chunlan Zhou was born in China, in 1977. She received the bachelor’s degree from Lanzhou University, Lanzhou, China, in 2000, and the Ph.D. degree from the Institute of High Energy Physics, Chinese Academy of Science, Beijing, China, in 2005. From 2005 to 2006, she was a Lecturer with the Institute of Low Energy Nuclear Physics, Beijing Normal University. Since 2006, she has been a Professor with the Institute of Electrical Engineering, Chinese Academy of Sciences, focusing on production technology of the high-efficiency solar cell, the potential induced degradation of solar cell, black silicon solar cell, and new generation solar cells.

Ke-Fan Wang was born in Dengzhou, Henan, China, in 1979. He received the bachelor's degree from University of Jinan, Jinan, China, in 2001, and the PhD degree from National Synchrotron Radiation Laboratory (NSRL), University of Science & Technology of China in 2006. Since 2018, he has been a Professor with the Henan University. He has been a visiting scholar to The Chinese University of Hong Kong. His research interests focus on the quantum dots intermediate band solar cells, black silicon solar cells, copper indium gallium selenium solar cells, inorganic perovskite solar cells and heterojunction with intrinsic thin-layer silicon solar cells.

Corresponding author: Chunlan Zhou, zhouchl@mail.iee.ac.cn; Ke-Fan Wang, kfwang@henu.edu.cn

DOI: 10.1088/1674-4926/24030032CSTR: 32376.14.1674-4926.24030032

Abstract: Here, p-type polysilicon films are fabricated by ex-situ doping method with ammonium tetraborate tetrahydrate (ATT) as the boron source, named ATT-pPoly. The effects of ATT on the properties of polysilicon films are comprehensively analyzed. The Raman spectra reveal that the ATT-pPoly film is composed of grain boundary and crystalline regions. The preferred orientation is the (111) direction. The grain size increases from 16−23 nm to 21−47 nm, by ~70% on average. Comparing with other reported films, Hall measurements reveal that the ATT-pPoly film has a higher carrier concentration (>10²⁰ cm⁻³) and higher carrier mobility (>30 cm²/(V·s)). The superior properties of the ATT-pPoly film are attributed to the heavy doping and improved grain size. Heavy doping property is proved by the mean sheet resistance (R_sheet,m) and distribution profile. The R_sheet,m decreases by more than 30%, and it can be further decreased by 90% if the annealing temperature or duration is increased. The boron concentration of ATT-pPoly film annealed at 950 °C for 45 min is ~3 × 10²⁰ cm⁻³, and the distribution is nearly the same, except near the surface. Besides, the standard deviation coefficient (σ) of R_sheet,m is less than 5.0%, which verifies the excellent uniformity of ATT-pPoly film.

Key words: polysilicon film, boron doping, ammonium tetraborate tetrahydrate (ATT), electrical properties, crystallization

References

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Fig. 1. (Color online) Flow chart of the experimental process.

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Fig. 2. (Color online) Raman spectra and the corresponding deconvolution peaks of 150 nm silicon film (a) deposited by magnetic sputtering (p:a-Si), (b) annealed directly at 950 °C for 45 min (pPoly film), and (c) annealed with spin-coated ATT at 950 °C for 45 min (ATT-pPoly film). (d) XRD patterns of the three samples.

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Fig. 3. (Color online) Effect of ATT on the average grain size (δ). (a) Particle size obtained through log-normal and Gaussian distributions. Inset: a typical SEM image of the annealed polysilicon film; (b) the average grain size δ of pPoly and ATT-pPoly films annealed at 950 °C for 45 min under different sputtering thickness (d).

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Fig. 4. (Color online) Electrical properties of the p:poly-Si films vs. deposition thickness (d). (a) Resistivity (ρ), (b) carrier concentration (p^*), and (c) carrier mobility (μ).

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Fig. 5. (Color online) Mean sheet resistance (R_sheet,m) and the corresponding standard deviation coefficient (σ) vs. annealing temperature of the samples annealed for 45 min. The silicon films shown in (a) are deposited at a pressure of 0.2 Pa, and the samples in (b) are deposited at 0.5 Pa. The curves in (c) and (d) show uniformity.

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Fig. 6. (Color online) Mean sheet resistance (R_sheet,m) and the corresponding standard deviation coefficient (σ) vs. annealing duration at 900 °C. The silicon films shown in (a) are deposited at a pressure of 0.2 Pa and the sample in (b) is deposited at 0.5 Pa. The curves in (c) and (d) show uniformity.

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Fig. 7. (Color online) Boron concentration distribution in p:poly-Si films (annealed at 950 °C for 45 min) measured by SIMS.

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Table 1. Comparison between the electrical properties of proposed and previously reported boron-doped p:poly-Si films.

Film		Dopant		Carrier		Ref.
Deposition method	Thickness d (nm)	Source	Progress	Concentration p^* (cm⁻³)	Mobility μ (cm²/(V·s))	Ref.
LPCVD + laser crystallizing	150	BF₂, implantation	RTA: 950 °C	4.30 × 10¹⁹	22.94	[43]
LPCVD + laser crystallizing	150	BF₂, implantation	CO₂ laser annealing: 135 W	1.92 × 10¹⁹	18.06	[43]
LPCVD + annealing (550/590) S-MIC^a	100	B, implantation	Annealing: 900 °C	~3 × 10¹⁹	~32	[44]
LPCVD + annealing (1000 °C)	550	B, implantation	Annealing: 1000 °C	1.7 × 10¹⁹	~22.5	[45]
Electron beam evaporation + MILE^b	170	Thermal effusion cells (B: HTS-W): 1950 °C	Annealing: 800 °C, 100 mbar	3.2 × 10¹⁹	11.2	[46]
APCVD	~5000	BBr₃: in-situ	880 °C	3.9 × 10¹⁹	~14.8	[47]
APCVD	~4100	BBr₃: in-situ	880 °C	3.4 × 10¹⁹	~15	[48]
PECVD + laser crystallizing	50	B₂H₆: implantation	Forming gas: 650 °C	~7 × 10¹⁹	~10	[49]
Sputter	150	ATT	Annealing: 950 °C	1.73 × 10²⁰	32.5	This work
Sputter	80	ATT	Annealing: 950 °C	4.24 × 10²⁰	31.9	This work
^a S-MIC: solution-based metal-induced crystallization; ^b MILE: metal-induced layer exchange.

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[23]	Ding Z T, Yan D, Stuckelberger J, et al. Phosphorus-doped polycrystalline silicon passivating contacts via spin-on doping. Sol Energy Mater Sol Cells, 2021, 221, 110902 doi: 10.1016/j.solmat.2020.110902
[24]	Park H J, Kim J, Choi D, et al. Boron-doped polysilicon using spin-on doping for high-efficiency both-side passivating contact silicon solar cells. Prog Photovolt Res Appl, 2023, 31, 461 doi: 10.1002/pip.3648
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[26]	Padhamnath P, Buatis J K, Khanna A, et al. Characterization of screen printed and fire-through contacts on LPCVD based passivating contacts in monoPoly™ solar cells. Sol Energy, 2020, 202, 73 doi: 10.1016/j.solener.2020.03.087
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[28]	Devasia S, Shaji S, Avellaneda D A, et al. In situ crystallization of 0D perovskite derivative Cs₃Bi₂I₉ thin films via ultrasonic spray. J Alloys Compd, 2022, 893, 162294 doi: 10.1016/j.jallcom.2021.162294
[29]	Teng X P, Chen J, Sun B S, et al. Study on the nucleation and growth of In₂O₃ powders for oxide ceramic targets. J Alloys Compd, 2022, 921, 166130 doi: 10.1016/j.jallcom.2022.166130
[30]	Padhamnath P, Nampalli N, Khanna A, et al. Progress with passivation and screen-printed metallization of Boron-doped monoPoly™ layers. Sol Energy, 2022, 231, 8 doi: 10.1016/j.solener.2021.11.015
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Received: 23 March 2024 Revised: 13 June 2024 Online: Accepted Manuscript: 04 July 2024Uncorrected proof: 09 July 2024Published: 15 October 2024

Article Navigation > Journal of Semiconductors > 2024 > 45(10): 102302

Yehua Tang, Yuchao Wang, Chunlan Zhou, Ke-Fan Wang. Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate[J]. Journal of Semiconductors, 2024, 45(10): 102302. doi: 10.1088/1674-4926/24030032 ****Y H Tang, Y C Wang, C L Zhou, and K F Wang, Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate[J]. J. Semicond., 2024, 45(10), 102302 doi: 10.1088/1674-4926/24030032

Citation:

Yehua Tang, Yuchao Wang, Chunlan Zhou, Ke-Fan Wang. Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate[J]. Journal of Semiconductors, 2024, 45(10): 102302. doi: 10.1088/1674-4926/24030032 ****

Y H Tang, Y C Wang, C L Zhou, and K F Wang, Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate[J]. J. Semicond., 2024, 45(10), 102302 doi: 10.1088/1674-4926/24030032

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Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate

DOI: 10.1088/1674-4926/24030032

CSTR: 32376.14.1674-4926.24030032

Yehua Tang^{1, §},
Yuchao Wang^{2, 3, §},
Chunlan Zhou^{3, 4,},
Ke-Fan Wang^5,

1.
Electrical and Energy Engineering Department, Nantong Institute of Technology, Nantong 226000, China
2.
Ningxia Research Center of Silicon Target and Silicon-Carbon Negative Materials Engineering Technology, School of Materials Science and Engineering, North Minzu University, Yinchuan 750021, China
3.
Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100049, China
4.
School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
5.
Henan Key Laboratory of Quantum Materials and Quantum Energy, School of Future Technology, Henan University, Kaifeng 475004, China

More Information

Yehua Tang was born in China, in 1982. She received the bachelor’s degree from Yunnan Normal University, Yunnan, China, in 2004, and the Ph.D. degree from the Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China, in 2013. From 2013 to 2019, she was a R & D director with the Eoplly New Energy Technology Co., Ltd., Nantong, Jiangsu, China. From 2019 to 2023, she has been an associated professor with the Henan University. Since 2023, she has been a Professor with Electrical and Energy Engineering Department, Nantong Institute of Technology, focusing on production technology of n-Si solar cells
Chunlan Zhou was born in China, in 1977. She received the bachelor’s degree from Lanzhou University, Lanzhou, China, in 2000, and the Ph.D. degree from the Institute of High Energy Physics, Chinese Academy of Science, Beijing, China, in 2005. From 2005 to 2006, she was a Lecturer with the Institute of Low Energy Nuclear Physics, Beijing Normal University. Since 2006, she has been a Professor with the Institute of Electrical Engineering, Chinese Academy of Sciences, focusing on production technology of the high-efficiency solar cell, the potential induced degradation of solar cell, black silicon solar cell, and new generation solar cells
Ke-Fan Wang was born in Dengzhou, Henan, China, in 1979. He received the bachelor's degree from University of Jinan, Jinan, China, in 2001, and the PhD degree from National Synchrotron Radiation Laboratory (NSRL), University of Science & Technology of China in 2006. Since 2018, he has been a Professor with the Henan University. He has been a visiting scholar to The Chinese University of Hong Kong. His research interests focus on the quantum dots intermediate band solar cells, black silicon solar cells, copper indium gallium selenium solar cells, inorganic perovskite solar cells and heterojunction with intrinsic thin-layer silicon solar cells
Corresponding author: zhouchl@mail.iee.ac.cn; kfwang@henu.edu.cn
Received Date: 2024-03-23
Revised Date: 2024-06-13

Available Online: 2024-07-04

Abstract

Abstract

Here, p-type polysilicon films are fabricated by ex-situ doping method with ammonium tetraborate tetrahydrate (ATT) as the boron source, named ATT-pPoly. The effects of ATT on the properties of polysilicon films are comprehensively analyzed. The Raman spectra reveal that the ATT-pPoly film is composed of grain boundary and crystalline regions. The preferred orientation is the (111) direction. The grain size increases from 16−23 nm to 21−47 nm, by ~70% on average. Comparing with other reported films, Hall measurements reveal that the ATT-pPoly film has a higher carrier concentration (>10²⁰ cm⁻³) and higher carrier mobility (>30 cm²/(V·s)). The superior properties of the ATT-pPoly film are attributed to the heavy doping and improved grain size. Heavy doping property is proved by the mean sheet resistance (R_sheet,m) and distribution profile. The R_sheet,m decreases by more than 30%, and it can be further decreased by 90% if the annealing temperature or duration is increased. The boron concentration of ATT-pPoly film annealed at 950 °C for 45 min is ~3 × 10²⁰ cm⁻³, and the distribution is nearly the same, except near the surface. Besides, the standard deviation coefficient (σ) of R_sheet,m is less than 5.0%, which verifies the excellent uniformity of ATT-pPoly film.
- polysilicon film,
- boron doping,
- ammonium tetraborate tetrahydrate (ATT),
- electrical properties,
- crystallization

^§These authors contributed equally to this work.

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