Thin film transistors (TFTs) are key components for the fabrication of electronic and optoelectronic devices, resulting in a push for the wider exploration of semiconducting materials and ...cost‐effective synthesis processes. In this report, a simple approach is proposed to achieve 2‐nm‐thick indium oxide nanosheets from liquid metal surfaces by employing a squeeze printing technique and thermal annealing at 250 °C in air. The resulting materials exhibit a high degree of transparency (>99 %) and an excellent electron mobility of ≈96 cm2 V−1 s−1, surpassing that of pristine printed 2D In2O3 and many other reported 2D semiconductors. UV‐detectors based on annealed 2D In2O3 also benefit from this process step, with the photoresponsivity reaching 5.2 × 104 and 9.4 × 103 A W−1 at the wavelengths of 285 and 365 nm, respectively. These values are an order of magnitude higher than for as‐synthesized 2D In2O3. Utilizing transmission electron microscopy with in situ annealing, it is demonstrated that the improvement in device performances is due to nanostructural changes within the oxide layers during annealing process. This work highlights a facile and ambient air compatible method for fabricating high‐quality semiconducting oxides, which will find application in emerging transparent electronics and optoelectronics.
2‐nm‐thick indium oxide nanosheets with high electron mobility have been synthesized utilizing a liquid metal printing technique and thermal annealing in air. Transmission electron microscopy with in situ annealing reveals that the improvement in device performances is due to nanostructural changes during annealing process. This work highlights a facile and ambient air compatible method for fabricating high‐quality semiconductors, which find application in emerging electronics and optoelectronics.
2D materials with high in‐plane anisotropy are rapidly emerging as a tantalizing class of nanomaterials with promising applications in nanoelectronics and optoelectronics since they provide an ...additional degree of freedom that can be exploited in device design. The large‐area synthesis of such materials remains however challenging since the anisotropic crystal structure renders identifying a suitable growth substrate to be difficult, while the nanosheets are usually too fragile for the exfoliation and transfer of macroscopic sheets. This work reports the scalable synthesis of highly crystalline, large‐area 2D Bi2S3 nanosheets using a novel liquid‐metal‐based synthesis approach. Ultrathin bismuth oxide sheets are exfoliated from molten bismuth followed by tube furnace sulfurization. The strategy effectively separates the formation of layered structures from the process of anisotropic crystallization, overcoming the shortcomings of established techniques. The synthesized nanosheets feature a highly anisotropic orthorhombic crystal structure with intraplane van der Waals gaps and a direct bandgap of ≈2.3 eV. The nanosheets are found to be highly photoconductive with a photoresponsivity of 8 A W−1. Bi2S3 channel‐based field effect transistors feature a maximum hole mobility of 28 cm2 V−1 s−1, highlighting the excellent electronic properties of the isolated nanosheets.
This work broadens the scalable synthesis and application of anisotropic 2D Bi2S3 nanosheets for potential optoelectronic devices. The synthesis method results in large lateral size nanosheets of Bi2S3 which are highly in‐plane anisotropy and p‐type semiconductivity. Photodetection and field effect transistor devices with 2D Bi2S3 channel exhibit a good responsivity of 8 A W−1 and a maximum mobility of 28 cm2 V−1 s−1.
We report the synthesis of centimeter sized ultrathin GaN and InN. The synthesis relies on the ammonolysis of liquid metal derived two-dimensional (2D) oxide sheets that were squeeze-transferred onto ...desired substrates. Wurtzite GaN nanosheets featured typical thicknesses of 1.3 nm, an optical bandgap of 3.5 eV and a carrier mobility of 21.5 cm2 V–1 s–1, while the InN featured a thickness of 2.0 nm. The deposited nanosheets were highly crystalline, grew along the (001) direction and featured a thickness of only three unit cells. The method provides a scalable approach for the integration of 2D morphologies of industrially important semiconductors into emerging electronics and optical devices.
High dielectric constant (high-k) ultrathin films are required as insulating gate materials. The well-known high-k dielectrics, including HfO2, ZrO2, and SrTiO3, feature three-dimensional lattice ...structures and are thus not easily obtained in the form of distinct ultrathin sheets. Therefore, their deposition as ultrathin layers still imposes challenges for electronic industries. Consequently, new high-k nanomaterials with k in the range of 40 to 100 and a band gap exceeding 4 eV are highly sought after. Antimony oxide nanosheets appear as a potential candidate that could fulfill these characteristics. Here, we report on the stoichiometric cubic polymorph of 2D antimony oxide (Sb2O3) as an ideal high-k dielectric sheet that can be synthesized via a low-temperature, substrate-independent, and silicon-industry-compatible liquid metal synthesis technique. A bismuth–antimony alloy was produced during the growth process. Preferential oxidation caused the surface of the melt to be dominated by α-Sb2O3. This ultrathin α-Sb2O3 was then deposited onto desired surfaces via a liquid metal print transfer. A tunable sheet thickness between ∼1.5 and ∼3 nm was achieved, while the lateral dimensions were within the millimeter range. The obtained α-Sb2O3 exhibited high crystallinity and a wide band gap of ∼4.4 eV. The relative permittivity assessment revealed a maximum k of 84, while a breakdown electric field of ∼10 MV/cm was observed. The isolated 2D α-Sb2O3 nanosheets were utilized in top-gated field-effect transistors that featured low leakage currents, highlighting that the obtained material is a promising gate oxide for conventional and van der Waals heterostructure-based electronics.
Due to excellent gas sensing performances, such as high responsivity, good selectivity, and long-term stability, two-dimensional (2D) nonlayered metal oxide semiconductors have attracted wide ...attention. However, their thickness-dependent gas sensing behaviors are rarely investigated, which is critical in the development of practical 2D sensors. In this work, 2D In2O3 crystals with a range of thicknesses are realized by extracting the self-limited oxide layer from the liquid indium droplets in a controlled environment. A strong thickness-dependent optoelectronic NO2 sensing behavior at room temperature is observed. While full reversibility and excellent selectivity toward NO2 are shown despite the thicknesses of 2D In2O3, the 1.9 nm thick In2O3 exhibits a maximum response amplitude (ΔI/I g = 1300) for 10 ppm of NO2 at room temperature with 365 nm light irradiation, which is about 18, 58, and 810 times larger than those of its 3.1 nm thick, 4.5 nm thick, and 6.2 nm thick counterparts, respectively. The shortest response and recovery times (i.e., 40 s/48 s) are demonstrated for the 1.88 nm thick In2O3 as well. We correlate such a phenomenon with the change in the In2O3 band structure, which is influenced by the thickness of 2D crystals. This work provides in-depth knowledge of the thickness-dependent gas-sensing performances of emerging 2D nonlayered metal oxide crystals, as well as the opportunities to develop next-generation high-performing room-temperature gas sensors.
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Metal-organic frameworks (MOFs) nanocomposites are under the limelight due to their unique electronic, optical, and surface properties for various applications. Plasmonic MOFs enabled ...by noble metal nanostructures are an emerging class of MOF nanocomposites with efficient solar light-harvesting capability. However, major concerns such as poor photostability, sophisticated synthesis processes, and high fabrication cost are raised. Here, we develop a novel plasmonic MOF nanocomposite consisting of the ultra-thin degenerately doped molybdenum oxide core and the flexible iron MOF (FeMOF) shell through a hydrothermal growth, featuring low cost, facile synthesis, and non-toxicity. More importantly, the incorporation of plasmonic oxides in the highly porous MOF structure enhances the visible light absorbability, demonstrating improved photobleaching performances of various azo and non-azo dyes compared to that of pure FeMOF without the incorporation of oxidative agents. Furthermore, the nanocomposite exhibits enhanced sensitivity and selectivity towards NO2 gas at room temperature, attributed to the electron-rich surface of plasmonic oxides. This work possibly broadens the exploration of plasmonic MOF nanocomposites for practical and efficient solar energy harvesting, environmental remediation, and environmental monitoring applications.
Ultrathin transparent conductive oxides (TCOs) are emerging candidates for next-generation transparent electronics. Indium oxide (In2O3) incorporated with post-transition-metal ions (e.g., Sn) has ...been widely studied due to their excellent optical transparency and electrical conductivity. However, their electron transport properties are deteriorated at the ultrathin two-dimensional (2D) morphology compared to that of intrinsic In2O3. Here, we explore the domain of transition-metal dopants in ultrathin In2O3 with the thicknesses down to the single-unit-cell limit, which is realized in a large area using a low-temperature liquid metal printing technique. Zn dopant is selected as a representative to incorporate into the In2O3 rhombohedral crystal framework, which results in the gradual transition of the host to quasimetallic. While the optical transmittance is maintained above 98%, an electron field-effect mobility of up to 87 cm2 V–1 s–1 and a considerable sub-kΩ–1 cm–1 ranged electrical conductivity are achieved when the Zn doping level is optimized, which are in a combination significantly improved compared to those of reported ultrathin TCOs. This work presents various opportunities for developing high-performance flexible transparent electronics based on emerging ultrathin TCO candidates.
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•MOF properties are modified by partially replacing Fe in PCN-250 by Co, Mn and Zn.•Fe2Mn displays an optimum NO2 response amongst other heterometallic PCN-250.•Optimum sensing ...performances of Fe2Mn are owing to its highest NO2binding energy.
Metal-organic frameworks (MOFs) with exceptional features such as high structural diversity and surface area as well as controlled pore size has been considered a promising candidate for developing room temperature highly-sensitive gas sensors. In comparison, the hetero-metallic MOFs with redox-active open-metal sites and mixed metal nodes may create peculiar surface properties and synergetic effects for enhanced gas sensing performances. In this work, the Fe atoms in the Fe3 (Porous coordination network) PCN-250 MOFs are partially replaced by transition metal Co, Mn, and Zn through a facile hydrothermal approach, leading to the formation of hetero-metallic MOFs (Fe2IIIMII, M = Co, Mn, and Zn). While the PCN-250 framework is maintained, the morphological and electronic band structural properties are manipulated upon the partial metal replacement of Fe. More importantly, the room temperature NO2 sensing performances are significantly varied, in which Fe2Mn PCN-250 demonstrates the largest response magnitude for ppb-level NO2 gas compared to those of pure Fe3 PCN-250 and other hetero-metallic MOF structures mainly attributed to the highest binding energy of NO2 gas. This work demonstrates the strong potential of hetero-metallic MOFs with carefully engineered substituted metal clusters for power-saving and high-performance gas sensing applications.
•Sol–gel derived SiC–SiO2 nanocomposite was prepared.•It effectively coated as AR layer on p-type Si-wafer.•SiC–SiO2 layer on Si solar cells exhibited relatively low reflectance of 7.08%.•Fabricated ...Si solar cell attained highly comparable performance of 16.99% to commercial device.
This paper describes the preparation, characterizations and the antireflection (AR) coating application in crystalline silicon solar cells of sol–gel derived SiC–SiO2 nanocomposite. The prepared SiC–SiO2 nanocomposite was effectively applied as AR layer on p-type Si-wafer via two step processes, where the sol–gel of precursor solution was first coated on p-type Si-wafer using spin coating at 2000rpm and then subjected to annealing at 450°C for 1h. The crystalline, and structural observations revealed the existence of SiC and SiO2 phases, which noticeably confirmed the formation of SiC–SiO2 nanocomposite. The SiC–SiO2 layer on Si solar cells was found to be an excellent AR coating, exhibiting the low reflectance of 7.08% at wavelengths ranging from 400 to 1000nm. The fabricated crystalline Si solar cell with SiC–SiO2 nanocomposite AR coating showed comparable power conversion efficiency of 16.99% to the conventional SixNx AR coated Si solar cell. New and effective sol–gel derived SiC–SiO2 AR layer would offer a promising technique to produce high performance Si solar cells with low-cost.
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