Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 5
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

Tin dioxide (SnO2) is an n-type semiconductor and has useful characteristics of high transmittance, excellent electrical properties, and chemical stability. Accordingly, it is widely used in a variety of fields, such as a gas sensor, photocatalyst, optoelectronics, and solar cell. In this study, SnO2 films are deposited by thermal atomic layer deposition (ALD) at 180°C using Tetrakis(dimethylamino)tin and water. A couple of 5.9, 7.4 and 10.1nm-thick SnO2 films are grown on SiO2/Si substrate and then each film is annealed at 400°C in oxygen atmosphere. Current transport of SnO2 films are analyzed by measuring current – voltage characteristics from room temperature to 150°C. It is concluded that electrical property of SnO2 film is concurrently affected by its semiconducting nature and oxidative adsorption on the surface.

Go to article

Authors and Affiliations

Seong Yu Yoon
Byung Joon Choi
ORCID: ORCID
Download PDF Download RIS Download Bibtex

Abstract

Among the various thin film coating techniques, atomic layer deposition (ALD) has features of good controllability of the thickness, excellent step-coverage in 3-dimensional object even in the sub-nm thickness range at the relatively low deposition temperature. In this study, SnO2 thin films were grown by ALD in the variation of substrate temperatures from 150 to 250°C. Even such a low temperature may influence on the growth kinetics of the ALD reaction and thus the physical characteristics of thin films, such as crystallinity, film density and optical band gap, etc. We observed the decrease of the growth rate with increasing substrate temperature, at the same time, the density of the film was decreased with increasing temperature. Steric hindrance effect of the precursor molecule was attributed to the inverse relationship of the growth temperature and growth rate as well as the film density. Optical indirect band gap energy (~3.6 eV) of the ALD-grown amorphous SnO2 films grown at 150°C was similar with that of the literature value, while slightly lower band gap energy (~3.4 eV) was acquired at the films grown at higher temperature.
Go to article

Authors and Affiliations

Daeho Kim
Dong Ha Kim
Doh-Hyung Riu
Byung Joon Choi
Download PDF Download RIS Download Bibtex

Abstract

Gadolinium oxide (Gd2O3) is one of the lanthanide rare-earth oxides, which has been extensively studied due to its versatile functionalities, such as a high permittivity, reactivity with moisture, and ionic conductivity, etc. In this work, GdOx thin film was grown by atomic layer deposition using cyclopentadienyl (Cp)-based Gd precursor and water. As-grown GdOx film was amorphous and had a sub-stoichiometric (x ~ 1.2) composition with a uniform elemental depth profile. ~3 nm-thick GdOx thin film could modify the hydrophilic Si substrate into hydrophobic surface with water wetting angle of 70°. Wetting and electrical test revealed that the growth temperature affects the hydrophobicity and electrical strength of the as-grown GdOx film.
Go to article

Bibliography

[1] C. Wiemer, L. Lamagna, M. Fanciulli, Semiconductor Science and Technology 27, 074013 (2012).
[2] A. Karimaghaloo, J. Koo, H. sen Kang, S.A. Song, J.H. Shim, M.H. Lee, International Journal of Precision Engineering and Manufacturing - Green Technology 6, 611 (2019).
[3] G . Azimi, R. Dhiman, H.M. Kwon, A.T. Paxson, K.K. Varanasi, Nature Materials 12, 315 (2013).
[4] I .K. Oh, K. Kim, Z. Lee, K.Y. Ko, C.W. Lee, S.J. Lee, J.M. Myung, C. Lansalot-Matras, W. Noh, C. Dussarrat, H. Kim, H.B.R. Lee, Chemistry of Materials 27, 148 (2015).
[5] M. Leskelä, K. Kukli, M. Ritala, Journal of Alloys and Compounds 418, 27 (2006).
[6] J.H. Han, A. Delabie, A. Franquet, T. Conard, S. van Elshocht, C. Adelmann, Chemical Vapor Deposition 21, 352 (2015).
[7] S. Govindarajan, T.S. Böscke, P. Sivasubramani, P.D. Kirsch, B.H. Lee, H.H. Tseng, R. Jammy, U. Schröder, S. Ramanathan, B.E. Gnade, Applied Physics Letters 91, 062906 (2007).
[8] H. Kim, H.J. Yun, B.J. Choi, RSC Advances 8, 42390 (2018).
[9] J.H. Shim, G.D. Han, H.J. Choi, Y. Kim, S. Xu, J. An, Y.B. Kim, T. Graf, T.D. Schladt, T.M. Gür, F.B. Prinz, International Journal of Precision Engineering and Manufacturing - Green Technology 6, 629 (2019).
[10] K. Xu, R. Ranjith, A. Laha, H. Parala, A.P. Milanov, R.A. Fischer, E. Bugiel, J. Feydt, S. Irsen, T. Toader, C. Bock, D. Rogalla, H.J. Osten, U. Kunze, A. Devi, Chemistry of Materials 24, 651 (2012).
[11] C. Adelmann, H. Tielens, D. Dewulf, A. Hardy, D. Pierreux, J. Swerts, E. Rosseel, X. Shi, M.K. van Bael, J.A. Kittl, S. van Elshocht, Journal of The Electrochemical Society 157, G105 (2010).
[12] D. Kim, D. Ha Kim, D.H. Riu, B.J. Choi, Archives of Metallurgy and Materials 63, 1061 (2018).
[13] M. Mishra, P. Kuppusami, S. Ramya, V. Ganesan, A. Singh, R. Thirumurugesan, E. Mohandas, Surface and Coatings Technology 262, 56 (2015).
[14] N.K. Sahoo, M. Senthilkumar, S. Thakur, D. Bhattacharyya, Applied Surface Science 200, 219 (2002).
Go to article

Authors and Affiliations

Sung Yeon Ryu
1
Hee Ju Yun
1
Min Hwan Lee
2
Byung Joon Choi
1
ORCID: ORCID

  1. Seoul National University of Science and Technology, Department of Material Science and Engineering, Seoul 01811, Korea
  2. University of California Merced, Department of Mechanical Engineering, Merced, California, USA
Download PDF Download RIS Download Bibtex

Abstract

Zinc oxide (ZnO) is a prominent n-type semiconductor material used in optoelectronic devices owing to the wide bandgap and transparency. The low-temperature growth of ZnO thin films expands diverse applications, such as growth on glass and organic materials, and it is also cost effective. However, the optical and electrical properties of ZnO films grown at low temperatures may be inferior owing to their low crystallinity and impurities. In this study, ZnO thin films were prepared by atomic layer deposition on SiO2 and glass substrates in the temperature range of 46-141℃. All films had a hexagonal würtzite structure. The carrier concentration and electrical conductivity were also investigated. The low-temperature grown films showed similar carrier concentration (a few 1019 cm−3 at 141°C), but possessed lower electrical conductivity compared to high-temperature (>200°C) grown films. The optical transmittance of 20 nm thin ZnO film reached approximately 90% under visible light irradiation. Additionally, bandgap energies in the range of 3.23-3.28 eV were determined from the Tauc plot. Overall, the optical properties were comparable to those of ZnO films grown at high temperature.
Go to article

Authors and Affiliations

Ji Young Park
1
ORCID: ORCID
Ye Bin Weon
1
ORCID: ORCID
Myeong Jun Jung
1
ORCID: ORCID
Byung Joon Choi
1
ORCID: ORCID

  1. Seoul National University of Science and Technology, Department of Material Science and Engineering, Seoul, Korea
Download PDF Download RIS Download Bibtex

Abstract

The sintering behavior of p-type bismuth telluride powder is investigated by means of dilatometric analysis. The alloy powders, prepared by ball milling of melt-spun ribbons, exhibit refined and flake shape. Differential thermal analysis reveals that the endothermic peak at about 280oC corresponds to the melting of bismuth, and peaks existing between 410oC and 510oC are presumably due to the oxidation and crystallization of the powder. The shrinkage behavior of ball-milled powders was strongly dependent of heating rate by the thermal effect exerted on specimens. In the case of 2oC/min, the peak temperature for the densification is measured at 406oC, while the peak temperature at a heating rate of 20oC/min is approximately 443oC. The relative density of specimen pressureless-sintered at 500oC exhibited relatively low value, and thus further study is required in order to increase the density of sintered body.

Go to article

Authors and Affiliations

Ju-Yeon Han
Jongmin Byun
ORCID: ORCID
Young-In Lee
ORCID: ORCID
Byung Joon Choi
ORCID: ORCID
Hogyoung Kim
Sung-Tag Oh
ORCID: ORCID

This page uses 'cookies'. Learn more