Effect of self-grown seed layer on thermoelectric properties of ZnO thin films

THIN SOLID FILMS

卷:605

Article

Saini, S.¹  Mele, P.²  Honda, H.³  Suzuki, T.³  Matsumoto, K.⁴  Miyazaki, K.⁵  Ichinose, A.⁶  Luna, L. Molina⁷  Carlini, R.⁸  Tiwari, A.¹ 

[1] Univ Utah, Dept Mat Sci & Engn, Salt Lake City, UT 84112 USA

[2] Muroran Inst Technol, Res Ctr Environm Friendly Mat Engn, Muroran, Hokkaido 050, Japan

[3] Hiroshima Univ, Dept Quantum Matter, ADSM, Higashihiroshima 724, Japan

[4] Kyushu Inst Technol, Dept Mat Sci, Kitakyushu, Fukuoka 804, Japan

[5] Kyushu Inst Technol, Dept Mech Engn, Kitakyushu, Fukuoka 804, Japan

[6] Cent Res Inst Elect Power Ind, Elect Power Engn Lab, Yokosuka, Kanagawa, Japan

[7] Tech Univ Darmstadt, Dept Mat & Geosci, Darmstadt, Germany

[8] Univ Genoa, Dept Chem & Ind Chem, Genoa, Italy

关键词: Self-grown seed layer;    c-axis orientation;    Al-doped ZnO thin films;    Pulsed laser deposition;    Seebeck coefficient;    High temperature applications;    Thermoelectric oxides;    Figure of merit;   

DOI  :  10.1016/j.tsf.2015.09.060

来源: Elsevier

【 摘 要 】

The influence of self-grown seed has been studied on thermoelectric performance of 2% Al-doped ZnO(AZO) thin films. The thickness and orientation of c-axis domains in seed layer change on different substrates while other deposition conditions were kept unchanged for a comparable study. The changes occur because of the different nucleation process of thin film growth on substrate interface and the different lattice mismatch between AZO and substrate. Thin films are grown by pulsed laser deposition on single crystals (SrTiO3 (STO) and Al2O3) and cheap amorphous fused silica (FS) substrates at 400 degrees C. All thin films are c-axis oriented. The grains are highly connected and elongated in shape which leads to high thermoelectric properties. The thicker self-grown seed layer is found in thin film deposited on FS substrates which shows best performance: electrical conductivity sigma = 93 S/cm and Seebeck coefficient S = -203 mu V/K, which estimate power factor (S-2.sigma) about 0.37 x 10(-3) Wm(-1)K(-2) at 600 K. The value of thermal conductivity (kappa) was found lowest (4.89 Wm(-1)K(-1)) for thin film deposited on FS than the other thin films (6.9 Wm(-1)K(-1) on Al2O3 and 6.55 Wm(-1)K(-1) on STO) at 300 K. The figure of merit, ZT = S-2.sigma.T/kappa, is calculated 0.046 at 600 K, 5 times larger than the ZT of our previous reported bulk AZO, which is promising for practical applications of thermoelectric oxide thin films. (C) 2015 Elsevier B.V. All rights reserved.

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