Epitaxial layered cobaltite NaxCoO2 thin films grown on planar and vicinal cut substrates

Yu, Li; Gu, Lin; Wang, Y.; Zhang, P. X.; Habermeier, H.‐U.

doi:10.1016/j.jcrysgro.2011.06.033

Cited by 15 publications

(11 citation statements)

References 26 publications

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“…[132][133][134][135][136][137][138][139] Several attempts resulted in epitaxial growth of Na x CoO 2 , on c-plane sapphire, SrTiO 3 , SrLaGaO 4 etc. 132,133,137,140 As sodium in these compounds is a reactive species, these films often suffered from poor stability. These stability issues were addressed using barrier or capping layers and the thermoelectric properties at room temperature were found to be largely stable and comparable to bulk single crystals.…”

Section: B Cobaltatesmentioning

confidence: 99%

Thermoelectric and thermal transport properties of complex oxide thin films, heterostructures and superlattices

Ravichandran

2016

J. Mater. Res.

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Over the years, the search for high performance thermoelectric materials has been dictated by the "phonon glass and electron crystal (PGEC)" paradigm, which suggests that low band gap semiconductors with high atomic number elements and high carrier mobility are the ideal materials to achieve high thermoelectric figure of merit. Complex oxides provide alternative mechanisms such as large density of states and strong electron correlation for high thermoelectric efficiency, albeit having low carrier mobility. Due to vast structural and chemical flexibility, they provide a fertile playground to design high efficiency thermoelectric materials. Further, developments in oxide thin film growth methods have enabled synthesis of high quality, atomically precise low dimensional structures such as heterostructures and superlattices. These materials and structures act as excellent model systems to explore nanoscale thermal and thermoelectric transport, which will not only expand the frontier of our knowledge, but also continue to enable cutting edge applications.

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Section: B Cobaltatesmentioning

confidence: 99%

Thermoelectric and thermal transport properties of complex oxide thin films, heterostructures and superlattices

Ravichandran

2016

J. Mater. Res.

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“…Thin films of Na x CoO 2 could serve as the building blocks for such superlattice structures and have already been investigated in previous studies. [14][15][16][17][18][19] However, no detailed analysis of the thermoelectric properties of these thin films has been performed to date, due to chemical instability of the thin films at ambient conditions. 14 Here, we present a method to obtain single phase thin films of Na x CoO 2 , which are chemically stable in ambient conditions.…”

Section: Introductionmentioning

confidence: 99%

Achieving chemical stability in thermoelectric NaxCoO2 thin films

et al. 2012

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Stability issues in thermoelectric Na x CoO 2 thin films have been solved by the addition of an in situ amorphous AlO x capping layer, which prevents previously reported degradation when exposed to air. These chemically stable thin films enable detailed analysis of the intrinsic thermoelectric properties and form a significant progress towards applications. Single phase Na x CoO 2 thin films with a low surface roughness are grown by pulsed laser deposition with either an epitaxial or textured crystal structure on Al 2 O 3 (001) or LaAlO 3 (001) single crystal substrates, respectively. For textured thin films a resistivity and thermopower of 0.99 mV cm and 69 mV K 21 are observed at room temperature, respectively. Based on an estimated thermal conductivity for thin films, the dimensionless figure of merit is very comparable to Na x CoO 2 single crystals, demonstrating the effectiveness of the developed capping layer.

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“…Additionally, several studies have reported research on Na x CoO 2 thin films, but most of them focus on the structural properties (Hildebrandt, Komissinskiy, Major, Donner, & Alff, 2013;Krockenberger et al, 2005Krockenberger et al, , 2006Son, 2008;Son, Kim, & Cho, 2005;Son, Lee, & Cho 2007;Son, Shin, & Park, 2008;Sugiura et al, 2006b;Venimadhav et al, 2005;Yu, Gu, Wang, Zhang, & Habermeier, 2011;Yu, Krockenberger, Fritsch, & Habermeier, 2007;Zhang et al, 2005;Zhou et al, 2006). These reports mostly describe thin films deposited on Al 2 O 3 , LaAlO 3 and SrTiO 3 , where in all studies these films are c-axis oriented and in some cases also epitaxial (Krockenberger et al, 2005;Son et al, 2005;Venimadhav et al, 2005;Yu et al, 2011).…”

Section: Cobaltate Thin Filmsmentioning

confidence: 99%

“…Thin films deposited on (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.7 (LSAT) substrates exhibit the smallest reduction of crystallinity, although an additional peak is observed. Previous studies have reported the growth of Na x CoO 2 thin films on hexagonal (0001) Al 2 O 3 as well as on cubic (001) LaAlO 3 and (001) SrTiO 3 single-crystal substrates (Brinks et al, 2012;Krockenberger et al, 2005;Son et al, 2005Son et al, , 2008Venimadhav et al, 2005;Yu et al, 2011;Zhou et al, 2006). A 2q/u map scan is shown in Figure 14.8(b) for the Na x CoO 2 thin film deposited on LSAT, which reveals the presence of a sharp peak and a diffuse peak, which is even more clearly visible in Figure 14.8, where a rocking curve (u scan) is shown.…”

Section: Structural Propertiesmentioning

confidence: 99%