The influence of RF power on the electrical properties of sputtered amorphous In-Ga-Zn-O thin films and devices

Junfei Shi; Chengyuan Dong; Wenjun Dai; Jie Wu; Yuting Chen; Runze Zhan

doi:10.1088/1674-4926/34/8/084003

J. Semicond. > 2013, Volume 34 > Issue 8 > 084003, doi: 10.1088/1674-4926/34/8/084003

SEMICONDUCTOR DEVICES

The influence of RF power on the electrical properties of sputtered amorphous In-Ga-Zn-O thin films and devices

Junfei Shi¹, Chengyuan Dong^1,, Wenjun Dai², Jie Wu¹, Yuting Chen¹ and Runze Zhan¹

+ Author Affiliations

Corresponding author: Dong Chengyuan, Email:cydong@sjtu.edu.cn

Abstract: The influence of radio frequency (RF) power on the properties of magnetron sputtered amorphous indium gallium zinc oxide (a-IGZO) thin films and the related thin-film transistor (TFT) devices is investigated comprehensively. A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined. The results prove that the deposition rate sensitively depends on RF power. In addition, the carrier concentration increases from 0.91×10¹⁹ to 2.15×10¹⁹ cm^-3 with the RF power rising from 40 to 80 W, which may account for the corresponding decrease in the resistivity of the a-IGZO thin films. No evident impacts of RF power are observed on the surface roughness, crystalline nature and stoichiometry of the a-IGZO samples. On the other hand, optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W, as is supposed to result from the carrier-induced band-filling effect. The rise in RF power can also affect the performance of a-IGZO TFTs, in particular by increasing the field-effect mobility clearly, which is assumed to be due to the alteration of the extended states in a-IGZO thin films.

Key words: thin-film transistors, amorphous oxide semiconductors, magnetron sputtering, radio frequency power

References

[1]	Hoffman R L, Norris B J, Wager J F. ZnO-based transparent thin-film transistors. Appl Phys Lett, 2003, 82(5):733 doi: 10.1063/1.1542677
[2]	Nomura K, Ohta H, Ueda K, et al. Thin-film transistor fabricated in single-crystalline transparent oxide semiconductor. Science, 2003, 300(5623):1269 doi: 10.1126/science.1083212
[3]	Wager J F. Transparent electronics. Science, 2003, 300(5623):1245 doi: 10.1126/science.1085276
[4]	Fortunato E, Pereira L M N, Barquinha P M C, et al. High mobility indium free amorphous oxide thin film transistors. Appl Phys Lett, 2008, 92(22):22103 doi: 10.1063/1.2937473?journalCode=apl
[5]	Orita M, Ohta H, Hirano M, et al. Amorphous transparent conductive oxide InGaO₃(ZnO)_m (m≤4):a Zn4s conductor. Phil Mag B, 2001, 81(5):501 doi: 10.1080/13642810110045923
[6]	Nomura K, Ohta H, Takagi A, et al. Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors. Nature (London), 2004, 432(7016):488 doi: 10.1038/nature03090
[7]	Nomura K, Kamiya T, Ohta H, et al. Local coordination structure and electronic structure of the large electron mobility amorphous oxide semiconductor In-Ga-Zn-O:experiment and ab initio calculations. Phys Rev B, 2007, 75(3):035212 doi: 10.1103/PhysRevB.75.035212
[8]	Chen J B, Wang L, Su X Q. InGaZnO thin films grown by pulsed laser deposition. Vacuum, 2012, 86(9):1313 doi: 10.1016/j.vacuum.2011.12.001
[9]	Yabuta H, Sano M, Abe K, et al. High-mobility thin-film transistor with amorphous InGaZnO₄ channel fabricated by room temperature rf-magnetron sputtering. Appl Phys Lett, 2006, 89(11):112123 doi: 10.1063/1.2353811
[10]	Kang D, Lim H, Kim C, et al. Amorphous gallium indium zinc oxide thin film transistors:sensitive to oxygen molecules. Appl Phys Lett, 2007, 90(19):192101 doi: 10.1063/1.2723543
[11]	Park J S, Jeong J K, Mo Y G, et al. Improvements in the device characteristics of amorphous indium gallium zinc oxide thin-film transistors by Ar plasma treatment. Appl Phys Lett, 2007, 90(26):262106 doi: 10.1063/1.2753107
[12]	Lee J M, Cho I T, Lee J H, et al. Full-swing InGaZnO thin film transistor inverter with depletion load. Jpn J Appl Phys, 2009, 48(10):100202 doi: 10.1143/JJAP.48.100202
[13]	Moon Y K, Lee S, Kim D H, et al. Application of DC magnetron sputtering to deposition of InGaZnO films for thin film transistor devices. Jpn J Appl Phys, 2009, 48(3):031301 doi: 10.1143/JJAP.48.031301
[14]	Chiang H Q, McFarlane B R, Hong D, et al. Processing effects on the stability of amorphous indium gallium zinc oxide thin-film transistors. J Non-Cryst Solids, 2008, 354(19-25):2826 doi: 10.1016/j.jnoncrysol.2007.10.105
[15]	Lim W, Kim S H, Wang Y L, et al. Stable room temperature deposited amorphous InGaZnO₄ thin film transistors. J Vac Sci Technol B, 2008, 26(3):959 doi: 10.1116/1.2917075
[16]	Kamiya T, Nomura K, Hirano M, et al. Subgap states in transparent amorphous oxide semiconductor, In-Ga-Zn-O, observed by bulk sensitive X-ray photoelectron spectroscopy. Phys Status Solidi C, 2008, 5(9):3098 doi: 10.1002/pssc.v5:9
[17]	Zhu B L, Zhao X Z, Xu S, et al. Oxygen pressure dependences of structure and properties of ZnO films deposited on amorphous glass substrates by pulsed laser deposition. Jpn J Appl Phys, 2008, 47(4):2225 doi: 10.1143/JJAP.47.2225
[18]	Burstein E. Anomalous optical absorption limit in InSb₄. Phys Rev, 1954, 93(3):632 doi: 10.1103/PhysRev.93.632
[19]	Moss T S. The interpretation of the properties of indium antimonide. Proc Phys Soc Lond B, 1954, 67(10):775 doi: 10.1088/0370-1301/67/10/306
[20]	Powell M J. The physics of amorphous-silicon thin-film transistors. IEEE Trans Electron Devices, 1989, 36(12):2753 doi: 10.1109/16.40933
[21]	Nomura K, Kamiya T, Ohta H, et al. Relationship between non-localized tail states and carrier transport in amorphous oxide semiconductor In-Ga-Zn-O. Phys Status Solidi A, 2008, 205(8):1910 doi: 10.1002/pssa.v205:8

Fig. 1. The deposition rate and resistivity of the a-IGZO thin films at various RF powers of (a) oxygen-rich samples, Ar : O$_{2}$ $=$ 30 sccm : 3 sccm, and (b) oxygen-deficient samples, Ar : O$_{2}$ $=$ 30 sccm : 0 sccm. The other sputtering conditions are a working pressure of 3 mTorr and substrate temperature of 150 ℃.

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Fig. 2. Resistivity, carrier concentration and Hall mobility of a-IGZO thin films at various RF powers of oxygen-deficient samples, obtained from Hall measurements.

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Fig. 3. (a) Surface roughness of a-IGZO thin films at various RF powers, obtained from AFM measurement. (b) A-IGZO thin-film stoichiometry at various RF powers, obtained from XPS measurement.

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Fig. 4. Optical transmittance of oxygen-rich a-IGZO thin films prepared with various RF powers. The corresponding optical band-gap extraction and the optical band-gap values of the a-IGZO thin films at various RF powers are shown in the subset figures.

DownLoad: Full-Size Img PowerPoint

Fig. 5. The transfer characteristics of a-IGZO TFTs with various IGZO RF powers. $W/L$ $=$ 400/200 $\mu$m and $V_{\rm ds}$ $=$ 5 V.

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Table 1. Comparison of the typical parameters in a-IGZO TFTs with various RF powers during a-IGZO sputtering.

[1]	Hoffman R L, Norris B J, Wager J F. ZnO-based transparent thin-film transistors. Appl Phys Lett, 2003, 82(5):733 doi: 10.1063/1.1542677
[2]	Nomura K, Ohta H, Ueda K, et al. Thin-film transistor fabricated in single-crystalline transparent oxide semiconductor. Science, 2003, 300(5623):1269 doi: 10.1126/science.1083212
[3]	Wager J F. Transparent electronics. Science, 2003, 300(5623):1245 doi: 10.1126/science.1085276
[4]	Fortunato E, Pereira L M N, Barquinha P M C, et al. High mobility indium free amorphous oxide thin film transistors. Appl Phys Lett, 2008, 92(22):22103 doi: 10.1063/1.2937473?journalCode=apl
[5]	Orita M, Ohta H, Hirano M, et al. Amorphous transparent conductive oxide InGaO₃(ZnO)_m (m≤4):a Zn4s conductor. Phil Mag B, 2001, 81(5):501 doi: 10.1080/13642810110045923
[6]	Nomura K, Ohta H, Takagi A, et al. Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors. Nature (London), 2004, 432(7016):488 doi: 10.1038/nature03090
[7]	Nomura K, Kamiya T, Ohta H, et al. Local coordination structure and electronic structure of the large electron mobility amorphous oxide semiconductor In-Ga-Zn-O:experiment and ab initio calculations. Phys Rev B, 2007, 75(3):035212 doi: 10.1103/PhysRevB.75.035212
[8]	Chen J B, Wang L, Su X Q. InGaZnO thin films grown by pulsed laser deposition. Vacuum, 2012, 86(9):1313 doi: 10.1016/j.vacuum.2011.12.001
[9]	Yabuta H, Sano M, Abe K, et al. High-mobility thin-film transistor with amorphous InGaZnO₄ channel fabricated by room temperature rf-magnetron sputtering. Appl Phys Lett, 2006, 89(11):112123 doi: 10.1063/1.2353811
[10]	Kang D, Lim H, Kim C, et al. Amorphous gallium indium zinc oxide thin film transistors:sensitive to oxygen molecules. Appl Phys Lett, 2007, 90(19):192101 doi: 10.1063/1.2723543
[11]	Park J S, Jeong J K, Mo Y G, et al. Improvements in the device characteristics of amorphous indium gallium zinc oxide thin-film transistors by Ar plasma treatment. Appl Phys Lett, 2007, 90(26):262106 doi: 10.1063/1.2753107
[12]	Lee J M, Cho I T, Lee J H, et al. Full-swing InGaZnO thin film transistor inverter with depletion load. Jpn J Appl Phys, 2009, 48(10):100202 doi: 10.1143/JJAP.48.100202
[13]	Moon Y K, Lee S, Kim D H, et al. Application of DC magnetron sputtering to deposition of InGaZnO films for thin film transistor devices. Jpn J Appl Phys, 2009, 48(3):031301 doi: 10.1143/JJAP.48.031301
[14]	Chiang H Q, McFarlane B R, Hong D, et al. Processing effects on the stability of amorphous indium gallium zinc oxide thin-film transistors. J Non-Cryst Solids, 2008, 354(19-25):2826 doi: 10.1016/j.jnoncrysol.2007.10.105
[15]	Lim W, Kim S H, Wang Y L, et al. Stable room temperature deposited amorphous InGaZnO₄ thin film transistors. J Vac Sci Technol B, 2008, 26(3):959 doi: 10.1116/1.2917075
[16]	Kamiya T, Nomura K, Hirano M, et al. Subgap states in transparent amorphous oxide semiconductor, In-Ga-Zn-O, observed by bulk sensitive X-ray photoelectron spectroscopy. Phys Status Solidi C, 2008, 5(9):3098 doi: 10.1002/pssc.v5:9
[17]	Zhu B L, Zhao X Z, Xu S, et al. Oxygen pressure dependences of structure and properties of ZnO films deposited on amorphous glass substrates by pulsed laser deposition. Jpn J Appl Phys, 2008, 47(4):2225 doi: 10.1143/JJAP.47.2225
[18]	Burstein E. Anomalous optical absorption limit in InSb₄. Phys Rev, 1954, 93(3):632 doi: 10.1103/PhysRev.93.632
[19]	Moss T S. The interpretation of the properties of indium antimonide. Proc Phys Soc Lond B, 1954, 67(10):775 doi: 10.1088/0370-1301/67/10/306
[20]	Powell M J. The physics of amorphous-silicon thin-film transistors. IEEE Trans Electron Devices, 1989, 36(12):2753 doi: 10.1109/16.40933
[21]	Nomura K, Kamiya T, Ohta H, et al. Relationship between non-localized tail states and carrier transport in amorphous oxide semiconductor In-Ga-Zn-O. Phys Status Solidi A, 2008, 205(8):1910 doi: 10.1002/pssa.v205:8

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Received: 09 January 2013 Revised: 04 March 2013 Online: Published: 01 August 2013

Article Navigation > Journal of Semiconductors > 2013 > 34(8): 084003

Junfei Shi, Chengyuan Dong, Wenjun Dai, Jie Wu, Yuting Chen, Runze Zhan. The influence of RF power on the electrical properties of sputtered amorphous In-Ga-Zn-O thin films and devices[J]. Journal of Semiconductors, 2013, 34(8): 084003. doi: 10.1088/1674-4926/34/8/084003 J F Shi, C Y Dong, W J Dai, J Wu, Y T Chen, R Z Zhan. The influence of RF power on the electrical properties of sputtered amorphous In-Ga-Zn-O thin films and devices[J]. J. Semicond., 2013, 34(8): 084003. doi: 10.1088/1674-4926/34/8/084003.Export: BibTex EndNote

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J F Shi, C Y Dong, W J Dai, J Wu, Y T Chen, R Z Zhan. The influence of RF power on the electrical properties of sputtered amorphous In-Ga-Zn-O thin films and devices[J]. J. Semicond., 2013, 34(8): 084003. doi: 10.1088/1674-4926/34/8/084003.

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The influence of RF power on the electrical properties of sputtered amorphous In-Ga-Zn-O thin films and devices

doi: 10.1088/1674-4926/34/8/084003

1.
Center for Opto-Electronic Materials and Devices, National Engineering Laboratory for TFT-LCD Materials and Technologies, Shanghai Jiao Tong University, Shanghai 200240, China
2.
Infovision Optoelectronics(Kunshan) Co., Ltd, Kunshan 215300, China

Funds:

the National Natural Science Foundation of China 61136004

the State Key Development Program for Basic Research of China 2013CB328803

Project supported by the State Key Development Program for Basic Research of China (No. 2013CB328803) and the National Natural Science Foundation of China (No. 61136004)

More Information

Corresponding author: Dong Chengyuan, Email:cydong@sjtu.edu.cn
Received Date: 2013-01-09
Revised Date: 2013-03-04
Published Date: 2013-08-01

Abstract

Abstract

The influence of radio frequency (RF) power on the properties of magnetron sputtered amorphous indium gallium zinc oxide (a-IGZO) thin films and the related thin-film transistor (TFT) devices is investigated comprehensively. A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined. The results prove that the deposition rate sensitively depends on RF power. In addition, the carrier concentration increases from 0.91×10¹⁹ to 2.15×10¹⁹ cm^-3 with the RF power rising from 40 to 80 W, which may account for the corresponding decrease in the resistivity of the a-IGZO thin films. No evident impacts of RF power are observed on the surface roughness, crystalline nature and stoichiometry of the a-IGZO samples. On the other hand, optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W, as is supposed to result from the carrier-induced band-filling effect. The rise in RF power can also affect the performance of a-IGZO TFTs, in particular by increasing the field-effect mobility clearly, which is assumed to be due to the alteration of the extended states in a-IGZO thin films.
- thin-film transistors,
- amorphous oxide semiconductors,
- magnetron sputtering,
- radio frequency power

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References(21)

References

[1]	Hoffman R L, Norris B J, Wager J F. ZnO-based transparent thin-film transistors. Appl Phys Lett, 2003, 82(5):733 doi: 10.1063/1.1542677
[2]	Nomura K, Ohta H, Ueda K, et al. Thin-film transistor fabricated in single-crystalline transparent oxide semiconductor. Science, 2003, 300(5623):1269 doi: 10.1126/science.1083212
[3]	Wager J F. Transparent electronics. Science, 2003, 300(5623):1245 doi: 10.1126/science.1085276
[4]	Fortunato E, Pereira L M N, Barquinha P M C, et al. High mobility indium free amorphous oxide thin film transistors. Appl Phys Lett, 2008, 92(22):22103 doi: 10.1063/1.2937473?journalCode=apl
[5]	Orita M, Ohta H, Hirano M, et al. Amorphous transparent conductive oxide InGaO₃(ZnO)_m (m≤4):a Zn4s conductor. Phil Mag B, 2001, 81(5):501 doi: 10.1080/13642810110045923
[6]	Nomura K, Ohta H, Takagi A, et al. Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors. Nature (London), 2004, 432(7016):488 doi: 10.1038/nature03090
[7]	Nomura K, Kamiya T, Ohta H, et al. Local coordination structure and electronic structure of the large electron mobility amorphous oxide semiconductor In-Ga-Zn-O:experiment and ab initio calculations. Phys Rev B, 2007, 75(3):035212 doi: 10.1103/PhysRevB.75.035212
[8]	Chen J B, Wang L, Su X Q. InGaZnO thin films grown by pulsed laser deposition. Vacuum, 2012, 86(9):1313 doi: 10.1016/j.vacuum.2011.12.001
[9]	Yabuta H, Sano M, Abe K, et al. High-mobility thin-film transistor with amorphous InGaZnO₄ channel fabricated by room temperature rf-magnetron sputtering. Appl Phys Lett, 2006, 89(11):112123 doi: 10.1063/1.2353811
[10]	Kang D, Lim H, Kim C, et al. Amorphous gallium indium zinc oxide thin film transistors:sensitive to oxygen molecules. Appl Phys Lett, 2007, 90(19):192101 doi: 10.1063/1.2723543
[11]	Park J S, Jeong J K, Mo Y G, et al. Improvements in the device characteristics of amorphous indium gallium zinc oxide thin-film transistors by Ar plasma treatment. Appl Phys Lett, 2007, 90(26):262106 doi: 10.1063/1.2753107
[12]	Lee J M, Cho I T, Lee J H, et al. Full-swing InGaZnO thin film transistor inverter with depletion load. Jpn J Appl Phys, 2009, 48(10):100202 doi: 10.1143/JJAP.48.100202
[13]	Moon Y K, Lee S, Kim D H, et al. Application of DC magnetron sputtering to deposition of InGaZnO films for thin film transistor devices. Jpn J Appl Phys, 2009, 48(3):031301 doi: 10.1143/JJAP.48.031301
[14]	Chiang H Q, McFarlane B R, Hong D, et al. Processing effects on the stability of amorphous indium gallium zinc oxide thin-film transistors. J Non-Cryst Solids, 2008, 354(19-25):2826 doi: 10.1016/j.jnoncrysol.2007.10.105
[15]	Lim W, Kim S H, Wang Y L, et al. Stable room temperature deposited amorphous InGaZnO₄ thin film transistors. J Vac Sci Technol B, 2008, 26(3):959 doi: 10.1116/1.2917075
[16]	Kamiya T, Nomura K, Hirano M, et al. Subgap states in transparent amorphous oxide semiconductor, In-Ga-Zn-O, observed by bulk sensitive X-ray photoelectron spectroscopy. Phys Status Solidi C, 2008, 5(9):3098 doi: 10.1002/pssc.v5:9
[17]	Zhu B L, Zhao X Z, Xu S, et al. Oxygen pressure dependences of structure and properties of ZnO films deposited on amorphous glass substrates by pulsed laser deposition. Jpn J Appl Phys, 2008, 47(4):2225 doi: 10.1143/JJAP.47.2225
[18]	Burstein E. Anomalous optical absorption limit in InSb₄. Phys Rev, 1954, 93(3):632 doi: 10.1103/PhysRev.93.632
[19]	Moss T S. The interpretation of the properties of indium antimonide. Proc Phys Soc Lond B, 1954, 67(10):775 doi: 10.1088/0370-1301/67/10/306
[20]	Powell M J. The physics of amorphous-silicon thin-film transistors. IEEE Trans Electron Devices, 1989, 36(12):2753 doi: 10.1109/16.40933
[21]	Nomura K, Kamiya T, Ohta H, et al. Relationship between non-localized tail states and carrier transport in amorphous oxide semiconductor In-Ga-Zn-O. Phys Status Solidi A, 2008, 205(8):1910 doi: 10.1002/pssa.v205:8

The influence of RF power on the electrical properties of sputtered amorphous In-Ga-Zn-O thin films and devices

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