Se/Sn flux ratio effects on epitaxial SnSe thin films; crystallinity &amp; domain rotation

Nguyễn, Văn Quảng; Duong, Van Thiet; Nguyen, Thi Huong; Kang, Rakwon; Phạm, Anh Tuấn; Tran, Van Tam; Nguyen, Cao Khang; Duong, Anh Tuan; Phan, Thắng Bách; Kim, Jungdae; Cho, Sunglae

doi:10.1016/j.jallcom.2020.155680

Cited by 10 publications

(10 citation statements)

References 22 publications

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“…Orientation control in epitaxial films, dimensionality control of electronic state in superlattice films, , and highly controlled nanostructure in nanocomposite films , suggest that the films are promising for developing high-performance thermoelectric materials. Therefore, while large ZT has been first demonstrated in the single crystal SnSe, the SnSe films − as well as the textured polycrystalline SnSe , have been prepared as the practical SnSe. The n-type SnSe films have been prepared using thermal evaporation or chemical vapor deposition, but control of the film structures and thermoelectric properties in n-type SnSe films is insufficient.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Property of n-Type Bismuth-Doped SnSe Film: Influence of Characteristic Film Defect

Horide

Nakamura

Hirayama

et al. 2021

ACS Appl. Energy Mater.

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Highly aligned SnSe exhibits very high thermoelectric properties, and orientation control in films is very promising for developing high-performance thermoelectric modules. While SnSe films with intrinsic p-type nature have been reported, fabrication of the highly aligned n-type SnSe films is difficult due to thermodynamic restriction on the solubility of the doping elements. Here, highly oriented SnSe films doped with Bi were successfully fabricated using pulsed laser deposition. Characteristic film structures were observed: doped Bi in the SnSe matrix; domain boundaries with a spacing of ∼200 nm; self-organized Bi precipitates with a bimodal size distribution; and stacking faults. The most important result is observation of the n-type Hall resistivity and the n-type Seebeck coefficient. The stacking faults and the doped Bi in the films degraded the room-temperature Seebeck coefficient. While the electron carrier mobility in room temperature was smaller than that in the single crystal due to the domain boundary scattering, the domain boundary scattering was suppressed in the high temperature of 300 °C. Thus, the characteristic film structures significantly affect the thermoelectric properties of SnSe. The doped Bi in the SnSe matrix, the stacking faults, and the domain boundaries should be controlled for further improvement of the thermoelectric properties in the Bi-SnSe films, and the self-organized Bi nanoprecipitates are very promising for achieving high-performance Bi-SnSe with decreased thermal conductivity.

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Section: Introductionmentioning

confidence: 99%

Thermoelectric Property of n-Type Bismuth-Doped SnSe Film: Influence of Characteristic Film Defect

Horide

Nakamura

Hirayama

et al. 2021

ACS Appl. Energy Mater.

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“…19,20 At the same time, molecular beam epitaxy (MBE) growth of orthorhombic SnSe did not improve upon the structural quality over PLD. 21 In this study by Nguyen et al, MBE growth on a MgO substrate yielded multiple (100)-oriented films with varying in-plane rotationone epitaxial alignment minimized lattice mismatch and another minimized symmetry mismatch. Epitaxial integration of SnSe with III−V semiconductors will require mediating both aspects at the same time, a task we accomplish in this work by using a rocksalt PbSe buffer layer.…”

Section: Introductionmentioning

confidence: 86%

“…Bulk crystals of SnSe prepared via melt growth (Bridgman) are of exceptional structural quality, but thin films are frequently deposited via low-temperature chemical bath deposition or low-purity physical vapor deposition and exhibit a poor morphology . Recently, SnSe films with improved structural quality, judged by X-ray diffraction (XRD) rocking curve peak widths (∼0.1–0.2° out-of-plane tilt mosaicity), have been synthesized via pulsed laser deposition (PLD) on ionic rocksalt NaCl and MgO insulating substrates. , At the same time, molecular beam epitaxy (MBE) growth of orthorhombic SnSe did not improve upon the structural quality over PLD . In this study by Nguyen et al, MBE growth on a MgO substrate yielded multiple (100)-oriented films with varying in-plane rotationone epitaxial alignment minimized lattice mismatch and another minimized symmetry mismatch.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial Integration and Defect Structure of Layered SnSe Films on PbSe/III–V Substrates

Haidet

Hughes

Mukherjee

2022

Crystal Growth & Design

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We synthesize epitaxial films of SnSe, a van der Waals (vdW) layered semiconductor, on III−V substrates via molecular beam epitaxy. While direct deposition of SnSe on GaAs(001) surfaces results in polycrystalline growth, the structural similarity between the distorted rocksalt SnSe and a rocksalt PbSe interlayer facilitates ordered quasi-vdW epitaxy of SnSe with only discrete in-plane rotations arising from the lower film symmetry. Toward manipulating the layering of SnSe for improved mechanical, optoelectronic, and ferroelastic/ferroelectric properties, we show that SnSe/PbSe-on-III−V interfaces are structurally commensurate and chemically compatible enough for the passage of sub-unit-cell surface steps and threading dislocations with partial Burgers vectors into the layered lattice from the 3D template. Such interfaces and extended defects result in novel stacking in SnSe along with the potential to crosslink layers across the vdW gap and yield films of mixed dimensionality. We assess the prospect of thermal expansion mismatch relief via sliding vdW interfaces in a 3D/layered/3D-bonded heterostructure using PbSe/SnSe/PbSeon-InAs and find this to be ineffective against cracking as dislocation diffusion, grain boundaries, and crosslinking defects embrittle the heterostructure.

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“…Doping controls the carrier concentration ,,− as well as temperature dependence of the thermoelectric property. , Control of orientation and nanostructure is possible in films, and the in-plane thermoelectric module can be fabricated by combining p-type and n-type films . Therefore, various thermoelectric films have been prepared. − SnSe films have also been prepared on single-crystal substrates for p-type thermoelectric applications − and other applications . SnSe/SrTiO 3 (STO) films prepared using pulsed laser deposition (PLD) exhibit a power factor as high as that of the single crystal .…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric Property of SnSe Films on Glass Substrate: Influence of Columnar Grain Boundary on Carrier Scattering

Horide

Murakami

Ishimaru

et al. 2022

ACS Appl. Electron. Mater.

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Thermoelectric SnSe exhibits a very high figure of merit, and the a-axis orientation is needed because a high thermoelectric property is obtained along the bcplane. Here, in spite of the amorphous nature of glass, a-axis-oriented SnSe films were fabricated using pulsed laser deposition on a glass substrate, which is more practical than single-crystal oxide substrates. Transmission electron microscopy indicated that aaxis-oriented SnSe films with a columnar grain structure grew on amorphous SiO 2 . The electrical conductivity and the Seebeck coefficient at room temperature showed almost the same trend with respect to the hole concentration in both the SnSe/glass and SnSe/ single-crystal-substrate films. The electrical conductivity increased with increasing temperature more slowly in SnSe/glass films than in SnSe/single-crystal-substrate films. This indicates that the grain boundary contribution to carrier scattering is significant at high temperatures, while the grain boundary contribution is as strong as the orthorhombic domain boundary contribution at room temperature. In spite of the grain boundary effect, the power factor in SnSe/ glass was as high as that for single-crystal SnSe at high temperatures. Considering the grain boundary effect on electrical conductivity, the structure and process of SnSe films on amorphous substrates should be designed.

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Se/Sn flux ratio effects on epitaxial SnSe thin films; crystallinity & domain rotation

Cited by 10 publications

References 22 publications

Thermoelectric Property of n-Type Bismuth-Doped SnSe Film: Influence of Characteristic Film Defect

Thermoelectric Property of n-Type Bismuth-Doped SnSe Film: Influence of Characteristic Film Defect

Epitaxial Integration and Defect Structure of Layered SnSe Films on PbSe/III–V Substrates

Thermoelectric Property of SnSe Films on Glass Substrate: Influence of Columnar Grain Boundary on Carrier Scattering

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