Optimization of Gas Sensing Performance of Nanocrystalline SnO 2 Thin Films Synthesized by Magnetron Sputtering

SnO2/Co3O4 nanofibers (NFs) are synthesized by using a homopolar electrospinning system with double jets of positive polarity electric fields. The morphology and structure of SnO2/Co3O4 hetero-nanofibers are characterized by using field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectrometer (XPS). The analyses of SnO2/Co3O4 NFs by EDS and HRTEM show that the cobalt and tin exist on one nanofiber, which is related to the homopolar electrospinning and the crystallization during sintering. As a typical n-type semiconductor, SnO2 has the disadvantages of high optimal operating temperature and poor reproducibility. Comparing with SnO2, the optimal operating temperature of SnO2/Co3O4 NFs is reduced from 350°C to 250°C, which may be related to the catalysis of Co3O4. The response of SnO2/Co3O4 to 100-ppm ethanol at 250°C is 50.9, 9 times higher than that of pure SnO2, which may be attributed to the p–n heterojunction between the n-type SnO2 crystalline grain and the p-type Co3O4 crystalline grain. The nanoscale p–n heterojunction promotes the electron migration and forms an interface barrier. The synergy effects between SnO2 and Co3O4, the crystalline grain p–n heterojunction, the existence of nanofibers and the large specific surface area all jointly contribute to the improved gas sensing performance.

Section: Introductionmentioning

confidence: 99%

SnO₂/Co₃O₄ nanofibers using double jets electrospinning as low operating temperature gas sensor

Wang¹,

Fan²,

Tang³

2022

“…Owing to the rapid development of film technology, a large amount of oxide heterointerfaces among transition metal oxides (TMOs) have been fabricated intensively, exhibiting a lot of intriguing physical functionalities because of their unique electronic structure and properties. [1][2][3][4][5][6][7][8][9][10] One typical breakthrough was that the interface between two ABO 3 type perovskite insulators, e.g., LaAlO 3 and SrTiO 3 (LAO/STO), hosts a high-mobility two-dimensional electron gas (2DEG). [11] The conductive interface possesses quantities of fascinating properties such as ferromagnetism, [12][13][14] superconductivity, [15,16] and strong Rashba spin-orbit coupling (Rashba-SOC), [17] which results from the interfacial breaking of inversion symmetry.…”

Section: Introductionmentioning

confidence: 99%

Gate tunable Rashba spin-orbit coupling at CaZrO₃/SrTiO₃ heterointerface

Jiang¹,

Zhao²,

Ling³

et al. 2022

High mobility quasi two-dimensional electron gas found at the CaZrO3/SrTiO3 nonpolar heterointerface is attractive and provides a platform for the development of functional devices and nanoelectronics. Here we report that the carrier density and mobility at low temperature can be tuned by gate voltage at the CaZrO3/SrTiO3 interface. Furthermore, the magnitude of Rashba spin-orbit interaction can be modulated and increases with the gate voltage. Remarkably, the diffusion constant and the spin-orbit relaxation time can be strongly tuned by gate voltage. The diffusion constant increases by a factor of ~19.98 and the relaxation time is reduced by a factor of over three orders of magnitude while the gate voltage is swept from -50V to 100 V. These findings not only lay a foundation for further understanding the underlying mechanism of Rashba spin-orbit coupling, but also have great significance in developing various oxide functional devices.

“…Until now, Sb nanofilms have been mainly obtained by micromechanical exfoliation, [16] liquid phase exfoliation, [17] and van der Waals epitaxy. [18][19][20][21][22] In comparison, there are more advantages for the molecular beam epitaxy [23][24][25][26] method in fabricating high-purity ultrathin Sb nanofilms of specific thickness. Recently, the epitaxial growth of Sb nanofilms on the lattice matching substrates, such as Bi 2 Te 3 , Sb 2 Te 3 , [27] PdTe 2 , [9] Ge (111), [28] and Ag (111), [29] has been reported.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial growth of antimony nanofilms on HOPG and thermal desorption to control the film thickness*

Xing¹,

Lei²,

Dong³

et al. 2020

Group-V elemental nanofilms were predicted to exhibit interesting physical properties such as nontrivial topological properties due to their strong spin–orbit coupling, the quantum confinement, and surface effect. It was reported that the ultrathin Sb nanofilms can undergo a series of topological transitions as a function of the film thickness h: from a topological semimetal (h > 7.8 nm) to a topological insulator (7.8 nm > h > 2.7 nm), then a quantum spin Hall (QSH) phase (2.7 nm > h > 1.0 nm) and a topological trivial semiconductor (h > 1.0 nm). Here, we report a comprehensive investigation on the epitaxial growth of Sb nanofilms on highly oriented pyrolytic graphite (HOPG) substrate and the controllable thermal desorption to achieve their specific thickness. The morphology, thickness, atomic structure, and thermal-strain effect of the Sb nanofilms were characterized by a combination study of scanning electron microscopy (SEM), atomic force microscopy (AFM), and scanning tunneling microscopy (STM). The realization of Sb nanofilms with specific thickness paves the way for the further exploring their thickness-dependent topological phase transitions and exotic physical properties.