Chemical Vapor Deposition Method Research Articles

Space-Confined Growth of Ultrathin P-Type GeTe Nanosheets for Broadband Photodetectors.

As p-type phase-change degenerate semiconductors, crystalline and amorphous germanium telluride (GeTe) exhibit metallic and semiconducting properties, respectively. However, the massive structural defects and strong interface scattering in amorphous GeTe films significantly reduce their performance. In this work, two-dimensional (2D) p-type GeTe nanosheets are synthesized via a specially designed space-confined chemical vapor deposition (CVD) method, with the thickness of the GeTe nanosheets reduced to 1.9nm. The space-confined CVD method improves the crystallinity of ultrathin GeTe by lowering the partial pressure of the reactant gas, resulting in GeTe nanosheets with excellent p-type semiconductor properties, such as a satisfactory on/off ratio of 105. Temperature-dependent electrical measurements demonstrate that variable-range hopping and optical-phonon-assisted hopping mechanisms dominate transport behavior at low and high temperatures, respectively. GeTe devices exhibit significantly high responsivity (6589 and 2.2 A W-1 at 633 and 980nm, respectively) and detectivity (1.67 × 1011 and 1.3 × 108 Jones at 633 and 980nm, respectively), making them feasible for broadband photodetectors in the visible to near-infrared range. Furthermore, the fabricated GeTe/WS2 diode exhibits a rectification ratio of 103 at zero gate voltage. These satisfactory p-type semiconductor properties demonstrate that ultrathin GeTe exhibits enormous potential for applications in optoelectronic interconnection circuits.

Chemical Vapor Deposition Growth of Atomically Thin SnSb2Te4 Single Crystals Toward Fast Photodetection

AbstractSnSb2Te4 (SST), a ternary van der Waals (vdW) material, has been widely investigated during last decades for potential applications in superconductivity, thermoelectricity, and optoelectronics. Recently, atomically thin SST has been predicted to show abnormal electronic band structure evolutions, high carrier mobility, and strong light–matter interaction. However, controllable synthesis of such SST crystals has been a huge challenge. Herein, atomically thin SST flakes are prepared via a chemical vapor deposition (CVD) method by using SbCl3, SnCl4·5H2O, and Te as the precursors. Multiple structural characterizations reveal that the SST flakes are single crystals with high crystallinity. Due to the narrow bandgap of 0.42 eV, SST‐based photodetectors have a broadband spectrum detection range from visible light through communication bands (480–1550 nm). More importantly, benefiting from a high room‐temperature carrier mobility over 300 cm2 V−1 s−1, the SST photodetectors demonstrate a response/recovery time of tens of tens of microseconds, which exceeds most typical transition metal dichalcogenide (TMDC) flakes. In addition, the photodetector maintains high performance after being exposed to the air for 2 months, suggesting good environmental stability. These excellent performances suggest that the SST flakes are promising for next‐generation optoelectronics.

Molecular dynamics simulation of carbon nanotube growth under a tensile strain

We performed molecular dynamics simulations of carbon nanotube (CNT) to elucidate the growth process in the floating catalyst chemical vapor deposition method (FCCVD). FCCVD has two features: a nanometer-sized cementite (Fe3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_3$$\\end{document}C) particle whose melting point is depressed because of the larger surface-to-volume ratio and tensile strain between the growing CNT and the catalyst. The simulations, including these effects, demonstrated that the number of 6-membered rings of the (6,4) chiral CNT constantly increased at a speed of 1mm/s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${1}\\,{\ extrm{mm}/\ extrm{s}}$$\\end{document} at 1273K\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${1273}\\,{\ extrm{K}}$$\\end{document}, whereas those of the armchair and zigzag CNTs were stopped in the simulations and only reached half of the numbers for chiral CNT. Both the temperature and CNT chirality significantly affected CNT growth under tensile strain.

Lubricity performance of hydrogen-free CVD growth of graphene on copper particles as an additive in paraffin base oil

This study aims to examine the impact of carbon precursor materials, which are oil palm fiber (OPF) and waste polystyrene (PS), on friction and wear properties of paraffin base oil added with graphene-coated copper (Cu) additive. The graphene was synthesized on Cu particles via hydrogen-free chemical vapor deposition method. The graphene was characterized using Raman spectroscopy and transmission electron microscopy. The lubricity properties of 0.6 wt.% of synthesized graphene-coated Cu additive in paraffin base oil was analyzed based on its tribological behavior using a four-ball tribometer. From the quantitative and qualitative characterization analysis, graphene-coated Cu additive synthesized using 50 wt.% OPF carbon precursors has a good-quality graphene with minimal defects and a well-ordered lattice structure. From the tribological analysis, the paraffin base oil added with graphene-coated Cu additive synthesized using 50 wt.% OPF carbon precursor has the lowest coefficient of friction of 0.07 and wear rate of 1.6 × 10−5 mm3/min. Hence, it can be suggested that incorporating graphene-coated Cu particles, synthesized from a 50 wt.% OPF carbon precursor, into base oil shows great potential as an environmentally friendly additive, particularly in terms of enhancing lubrication performance.

Effect of Gas Flow Rate and Ratio on Structure and Properties of Nitrogen-Doped Diamond-like Carbon Films

Diamond-like carbon (DLC) has attracted much attention due to its unique properties such as high chemical inertness, optical transparency, and high biocompatibility. In this study, the total gas flow rate was kept constant, while the ratio of reactive gases was varied to deposit nitrogen-doped diamond-like carbon thin films on glass substrates using radiofrequency plasma-enhanced chemical vapor deposition. The effects of the gas flow ratio on the composition, microstructure, surface morphology, and optical properties of the thin films were investigated through extended deposition times. It was found that with an increase in the nitrogen-to-methane gas flow ratio, the film surface became smoother and more compact. The maximum transmittance in the visible range reached 90%, and the highest and lowest transmittance in the same ultraviolet wavelength region differed by up to 25.62% among several sample groups. The optical bandgap decreased from 3.58 eV to 3.46 eV, contrary to the trend of the sp2 fraction variation. Compared with other studies, this study considered the preparation of nitrogen-doped diamondoids using a chemical vapor deposition method with a lesser total gas flow rate passed into it, which provides practical data reference value for the preparation of N-DLC.

New approaches to the synthesis of substituted derivatives of the [B<sub>3</sub>H<sub>8</sub>]<sup>−</sup> anion

Objectives. To develop methods for the synthesis of substituted derivatives of the octahydrotriborate anion. Such compounds can be considered as hydrogen storage, components of ionic liquids, precursors for the production of boride coatings using the traditional chemical vapor deposition method, and also as a building material for the production of higher boron hydrogen clusters.Methods. Since substitution reactions are sensitive to moisture and atmospheric oxygen, the syntheses were carried out in a direct flow of argon or in a dry, sealed SPEKS GB02M glove box with a double gas purification unit and two airlocks. The reaction was initiated by cooling to 0°C, in order to avoid the formation of by-products. All the results were characterized using infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies.Results. The study presents a detailed study of the known methods for preparing substituted derivatives of the octahydrotriborate(1−) anion using dry hydrogen chloride as an electrophilic inductor and makes recommendations for improvement. In this method it is advisable to use cesium octahydrotriborate which facilitates the yield of the target product. New methods were proposed to initiate the substitution reaction in the [B3H8]−-anion using N-chlorosuccinimide and bromine. Using these inductors, new substituted derivatives of the octahydrotriborate anion with N-nucleophiles were obtained and defined by means of IR and NMR spectroscopies: [B3H7NCR], (R = Et, i-Pr, Ph) and [B3H7NH2R], (R = C9H19 (INA), Bn), [B3H7NHEt2], as well as Bu4N[B3H7Hal], Bu4N[B3H6Hal2], where Hal = Сl, Br. It was also established that hydrogen bromide is released during the reaction with bromine and amines. This immediately protonates the amine which requires additional heating of the reaction mixture. The study also established that the reaction mechanism with N-chlorosuccinimide is not radical.Conclusions. The main factors influencing the course of the substitution reaction are the possible occurrence of side interactions between the nucleophile and the inducer, steric possibilities, and subsequent isolation of the reactive reaction products.

Niobium doping of CVD-WS2 monolayers using solid precursors with and without salt-KBr as a catalyst: A comparative study

The in situ doping of tungsten disulfide (WS2) monolayers with Niobium (Nb) atoms was obtained through the atmospheric pressure chemical vapor deposition (APCVD) method by controlling the Nb2O5 and WO3 precursors mass ratios. Samples were prepared employing the same growth parameters with and without the use of KBr salt as a catalyst. In both cases, the Nb incorporation quenches the luminescence intensity of the doped samples, and it depends on the Nb2O5:WO3 mass ratio. X-ray photoelectron spectroscopy (XPS) measurements were performed, and the observed redshift at the Fermi level indicated p-type doping. Nb-doped WS2 monolayers synthesized without the use of the catalyst have lower defect density, as revealed by a careful Raman analysis, and are free of agglomerates on their monolayers’ basal plane. The use of KBr as the catalyst increases the average crystal size but also increases the disorder effects compared with samples prepared without the use of salt. The presence of agglomerates of impurities at the surface of doped samples was observed in samples prepared with the use of salt as a catalyst. The controlled synthesis of p-type WS2 with low defect density is essential for developing electronic and photonic devices based on WS2 material.

Chemical Vapor Deposition Synthesis of Intrinsic High-Temperature Ferroelectric 2D CuCrSe2.

Ultrathin 2D ferroelectrics with high Curie temperature are critical for multifunctional ferroelectric devices. However, the ferroelectric spontaneous polarization is consistently broken by the strong thermal fluctuations at high temperature, resulting in the rare discovery of high-temperature ferroelectricity in 2D materials. Here, a chemical vapor deposition method is reported to synthesize 2D CuCrSe2 nanosheets. The crystal structure is confirmed by scanning transmission electron microscopy characterization. The measured ferroelectric phase transition temperature of ultrathin CuCrSe2 is about ≈800 K. Significantly, the switchable ferroelectric polarization is observed in ≈5.2nm nanosheet. Moreover, the in-plane and out-of-plane ferroelectric response are modulated by different maximum bias voltage. This work provides a new insight into the construction of 2D ferroelectrics with high Curie temperature.

Unveiling structural and optical properties of Sn-doped β-Ga2O3: A correlation of experimental and theoretical observations

This work presents the experimental and theoretical insights into the structural and optical properties of tin (Sn)-doped β-Ga2O3. Sn-doped β-Ga2O3 films were fabricated using the low-pressure chemical vapor deposition (LPCVD) method onto the c-plane sapphire substrate. Further, deposited thin films were characterized for their structural and optical properties. XRD pattern depicts the crystalline nature of β-Ga2O3. The energy band gap (Eg) obtained from UV–Vis spectra has been decreased from 4.82 eV to 4.77 eV for as-deposited β-Ga2O3 to Sn-doped β-Ga2O3, respectively. However, an increase in absorbance has been observed in Sn-doped β-Ga2O3 films. Further, the first principle study based on density functional theory (DFT) has been used to comprehend the effect of Sn doping in β-Ga2O3 films. DFT result reveals the expansion of the lattice parameter of intrinsic β-Ga2O3 on the introduction of the Sn atom. Furthermore, a reduction in Eg has been observed upon Sn doping into the β-Ga2O3 structure similar to the experimental results. The reason behind the reduction in the Eg may be due to the Sn-5s energy level at the bottom of the conduction band as revealed in density of state (DOS) investigations. Also, the DOS results of Sn-doped β-Ga2O3 suggest that the atom has tended to form the ionic bond characteristics with the introduction of Sn into the β-Ga2O3, where the free electrons of the Sn-5s orbital state will fill the conduction band and may improve the conductivity. Additionally, optical properties such as reflectance and dielectric loss of function have been investigated. The reflectance and dielectric loss of function result proposed that more energy was absorbed when Sn was introduced to β-Ga2O3. Therefore, our observation suggests that upon Sn doping into β-Ga2O3, optical as well as structural properties were improved and these improved properties may be useful for optoelectronic devices.Novelty statementβ-Ga2O3 is an emerging material for optoelectronic device applications due to its excellent wide energy band gap, high critical electric field strength, high melting point, high Baliga figure of merits (BFOM), and exceptional physical and chemical stability. However, intrinsic β-Ga2O3 suffers from poor mobility and surface defects. Therefore, β-Ga2O3 needs a dopant material to enhance its' structural and optical properties. In this case, Sn doping may improve the optoelectronic properties of β-Ga2O3. Therefore, detailed theoretical and experimental investigations on Sn-doped β-Ga2O3 become necessary to understand inside phenomena. However, lots of experimental and theoretical works have been performed on Sn-doped β-Ga2O3. But, to date, there is no available report related to the correlation of theoretical and experimental data-based studies on Sn-doped β-Ga2O3. In this work, we have explored the structural and optical properties of Sn-doped β-Ga2O3 thin films deposited by the LPCVD method on the c-plane sapphire substrate. Further, the experimental results obtained were correlated with the first principal based DFT results. Our observation suggests that upon Sn doping into β-Ga2O3, optical as well as structural properties were improved and these improved properties may be useful for optoelectronic devices.

Blue-white electroluminescence of diamond/WS2 quantum dot composite films

Two kinds of diamond films with completely different morphologies were prepared on N-type heavily doped silicon wafers by microwave plasma chemical vapor deposition (MPCVD) method, namely, micron-scale large grain polycrystalline diamond film dominated by (220) crystal plane (220DF) and nano-scale small grain polycrystalline diamond film dominated by (111) crystal plane (111DF). And WS2 quantum dot powder was obtained by aqueous liquid phase ultrasonic method. Then, the 111DF/WS2 quantum dot composite structure film (111DWSF) and 220DF/WS2 quantum dot composite structure film (220DWSF) were prepared by applying WS2 quantum dot powder uniformly on diamond film substrate. The results of electroluminescence (EL) detection show that the 220DWSF device emits visible blue light, and the main peak of EL spectrum is located at 443 nm in the blue region. The 111DWSF device emits white light, and the corresponding EL spectra show strong emission peaks in the blue region (454 nm), green region (536 nm) and red region (632 nm) respectively, meanwhile, the luminous intensity of 111DWSF device is much higher than that of 220DWSF device. In addition, it is also found that the 220DWSF EL device does not show obvious rectification characteristics, while the 111DWSF EL device has obvious rectification characteristics. After FN fitting of the IV characteristic curve of 111DWSF EL device, the tunneling characteristics of electrons are found in the region of high electric field intensity.

Synthesis and characterization of carbon nanopearl chains on Co-Coated silicon substrate by CVD method

Carbon nanopearl chains (CNPCs) consisted of carbon nanospheres and carbon nanofibers were prepared by chemical vapor deposition (CVD) method using benzene as the carbon source and Co particles on Si-substrate as the catalyst. The characterized results confirmed that the carbon nanospheres with a diameter between 80 nm and 300 nm have solid structure and wavy graphite layered surface, while the carbon nanofibers (diameter: 16 nm) showed amorphous structure and excellent flexibility. Therefore, these synthesized CNPCs can be potentially applied as the reinforcing matrix. Moreover, the growth mechanism of CNPCs has also been proposed by investigating the effects of Co catalyst, thiophene promoter and gas-flow during the growth process.

Aerosol assisted chemical vapor deposition routes for the selective formation of gas sensitive iron oxide structures

Iron oxide (Fe2O3) structures with various morphologies are synthesized by aerosol-assisted chemical vapor deposition (AACVD) method. The structures are formed reproducibly by tuning different AACVD synthesis parameters, including temperatures, solvents, and samples' position in the reaction chamber. The properties of these structures are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Results demonstrate the formation of six types of crystalline Fe2O3 structures - flattened pyramids (fPy), pyramids (Py), porous pyramids (pPy), sheets (Sh), bricks (Br), and quasi-spherical particles (qsP). The formation of these structures is mainly connected with the use of acetone or acetone/ethanol mixture as solvents and their effect on boosting the influence of the temperature or sample’s position, respectively, on the properties of the structures. The gas sensing tests of the structures with higher aspect ratios or porosity (pPy, Py, fPy, and Sh) showed responses to various gases (acetone, ethanol, toluene, carbon monoxide, hydrogen, methane, ammonia, and nitrous oxide), reporting maximum sensitivity and selectivity to acetone and ethanol. The best results recorded are for the porous pyramids which show sensitivities of 5.1 % ppm−1 and 3.9 % ppm−1 (in the range of 10–40 ppm) to acetone and ethanol, respectively.

Fabrication and properties of lateral Josephson junctions with a RuO2 weak link

Ruthenium dioxide (RuO2) is a metallic rutile oxide with a number of interesting properties. For a long time, it was considered to be a highly conductive normal metal and a Pauli paramagnet. Recently, it was found that the material is antiferromagnetic, with small magnetic moments of the order of 0.05 Bohr magneton and an ordering temperature above 300 K. The presence of magnetic moments should have clear consequences when trying to induce superconductivity in RuO2. We used a selective area chemical vapor deposition method to grow nanostrips of RuO2 on TiO2 substrates. On these nanostrips, superconducting contacts were made of MoGe, and a weak link was fabricated with a Focused Ion Beam. We find that the device behaves as a Josephson junction, including a Fraunhofer-like response to a magnetic field, for distances between the contacts below 70 nm. We estimate the induced singlet coherence length ξ to be about 12 nm, which seems a reasonable number when small magnetic moments are present.

Effect of deposition temperature on the tribo-mechanical properties of nitrogen doped DLC thin film

The tribomechanical characteristics of diamond-like carbon (DLC) coatings are notably superior to other hard coatings, making them highly desirable for industrial applications. This study focuses on the synthesis of nitrogen-doped DLC (N-DLC) films through chemical vapor deposition (CVD) methods, with an emphasis on varying the deposition temperature. Comprehensive characterization techniques such as atomic force microscopy (AFM), scanning electron microscopy (SEM), and nanoindentation were employed to investigate the morphological and mechanical attributes of these coatings. The thickness of the films, measured using a Dektak profilometer, demonstrated an increase from 1.9 to 2.8 µm as the deposition temperature rose. Nanoindentation testing revealed that the film deposited at 900°C exhibited the highest hardness (H) and modulus of elasticity (E), measuring 21.95 and 208.3 GPa, respectively. Conversely, the film deposited at 1,000°C showed the lowest values, with H and E at 14.23a and 141.9 GPa, respectively. The H/E ratio of the coatings initially rose from 0.096 to 0.106 as the deposition temperature increased from 800°C to 900°C. However, for deposition temperatures exceeding 900°C the H/E ratio began to decline.

Metatungstate Chemical Vapor Deposition of WSe2: Substrate Effects, Shapes, and Morphologies

Owing to their exceptional properties, which are usually determined by the growth conditions, 2D transition metal dichalcogenides (TMDCs) offer numerous research directions for applications in the fields of spintronics, valleytronics, and optoelectronics. Here, we focus on the chemical vapor deposition (CVD) synthesis of WSe2 (tungsten diselenide) nanoclusters/nanoflakes by using a liquid precursor for tungsten (ammonium metatungstate) on Si/SiO2, fused silica, and sapphire substrates. Various WSe2 clusters with different sizes, thicknesses, and geometries were analyzed by means of optical and atomic force microscopy (AFM) and Raman spectroscopy. The observed structures were mostly WSe2 multilayers; however, monolayer formations were also found. They showed significant morphological differences, as well as wide nucleation density and size variations, possibly related to precursor/substrate surface interactions under the same CVD synthesis conditions. The largest WSe2 domains with a lateral size of up to hundreds of micrometers were observed on sapphire, probably caused by a higher growth rate of singular nucleation sites. WSe2 domains with irregular and triangular shapes were simultaneously identified on fused silica, whereas multilayered pyramidal WSe2 structures dominated in the case of Si/SiO2 substrates. The application of polarized Raman spectroscopy to precisely determine and differentiate the characteristic vibrational modes (A1g, E2g, and 2LA(M)) enabled the unambiguous identification of 2D and/or multilayered WSe2 formations with a high crystallinity level. The presented comparative analysis of samples prepared in relatively simple synthesis conditions (moderate working temperatures and ambient pressure) provides a base for further progress of the facile metatungstate CVD method and relevant opportunities for the exploration of 2D TMDC materials.

Optical and optoelectronic properties of gallium oxide films fabricated by the chemical vapour deposition method

The present work investigated the influence of growth time on the structural, optical, and optoelectronic properties of β-Ga2O3 films produced on Si substrates by the chemical vapour deposition method. The prepared films were characterized by X-ray diffraction, field-emission scanning electron microscope, and UV–Vis spectrophotometer. The films exhibited a mixed phase (β-α)-Ga2O3 crystal structure. The crystallite size ranged between 34.98 and 164.69 nm. The bandgap increased from 4.74 to 4.88 eV. The absorption and extinction coefficients were in the orders of 103 and 10−1, respectively. The refractive index, dispersive energy and single oscillator energy increased from 1.86 to 1.87, 19.24 to 28.64, and 8.36 to 9.54, respectively, with an increase of growth time. The oscillator strength, oscillator wavelength, third-order nonlinear optical susceptibility and dispersion of refractive index were in the orders of 10−4, 10−2, 10−10 and 10−9, respectively. The carrier concentration, optical conductivity, optical mobility, and optical resistivity were also evaluated. The real and imaginary dielectric constants, and plasmon frequency were also determined.

Functionalized MXene fiber electrode for the electrochemical sensing of urinary ammonia

The development of technologically advanced fiber-based flexible microelectrodes has been of extensive research interest in healthcare systems because of their unique construction and synergistic effect on multifunctional properties. In this work, we constructed functional MXene fiber (MXF) by a simple and versatile wet spinning method, and then, a well-aligned ZIF-67 nanoarray was grown in situ on the surface. Using the chemical vapor deposition (CVD) method, carbon nanotubes (CNTs) were produced on MXF via the pyrolysis of ZIF-67 and melamine. Finally, Pt nanoparticles were electrodeposited on the CNTs forest, and a Pt@CNTs/MXF electrode was obtained. Owing to the plethora of surface active sites and the synergistic effects between MXene, CNTs, and Pt nanoparticles, the as-fabricated fiber electrode enabled the precise detection of ammonia under alkaline conditions via differential pulse voltammetry (DPV), which exhibited a linear range of 0.1 μM–10 mM and a detection limit of 73.2 nM. Due to their good performance in ammonia detection, Pt@CNTs/MXF electrodes could be adopted to determine the ammonia concentration in urine for clinical estimation, which provides a practical approach for the diagnosis of urinary ammonia-associated diseases.

Photoluminescence enhancement of chemical vapor-deposited MoSe2 monolayers

The transition metal dichalcogenide (TMDC) materials have attracted a great interest owing to their superior features. The chemical vapor deposition (CVD) is very feasible to synthesis of TMDC materials. The thermal expansion coefficient difference between TMDC materials and substrate in the CVD synthesis can cause a strain, resulting in non-radiative recombination and PL decrement for these materials. Therefore, in this work, we studied acetone and isopropanol (IPA) treatment on the photoluminescence (PL) properties of CVD-grown MoSe2 monolayers. Firstly, monolayer MoSe2 flakes on SiO2/Si substrates were synthesized via the CVD method by optimizing synthesis parameters. The Raman and PL measurements were taken after acetone and IPA treatments were applied to grown samples. The results indicated an important PL enhancement was seen for acetone treatment. For IPA treatment, there was a PL peak position shifting with decreasing intensity due to its possible structural damage. The acetone, IPA, and transfer processes caused the releasing strain on MoSe2 by breaking the strong interaction between MoSe2 and substrate. For the whole treatment, PL peaks shift to blue with about 80 meV. As a result of the present study, acetone treatment was found as an easy and quick way to enhance radiative emission of CVD-grown MoSe2.

Enhanced Performance of All‐Inorganic Lead Halide Perovskite/MoS2 Heterojunction Photodetectors by Achieving Interfacial Carrier Separation

A heterojunction interface engineering aimed at improving the performance of all‐inorganic lead halide perovskite photodetectors (PDs) is demonstrated by coupling the two‐dimensional (2D) MoS2 materials with CsPbBr3 used in the chemical vapor deposition method in situ‐grown. The MoS2 carrier extraction layer facilitates electron injection, while the large injection barrier of the CsPbBr3/MoS2 heterojunction depletion layer keeps holes in the perovskite layer, resulting in effective separation of photogenerated carriers at the heterojunction interface. Moreover, the photoluminescence quenching and lifetime shortening of the heterojunction further prove that there is a large amount of charge transfer between the CsPbBr3 and MoS2 interface. As a result, PDs based on the CsPbBr3/MoS2/interdigitated array electrodes (IDA) heterojunction exhibit remarkable performance, such as high photoresponsivity (23.4 A W−1), detectivity (1.48 × 1013 Jones), and switching ratio (1.35 × 105), all of which are an order of magnitude better than pure CsPbBr3 PDs. The heterojunction PD also presents a superior response time (0.07 ms).

Growth of 2D MoS2 on sapphire and mica

In this work, we present a study on the epitaxial growth of MoS2 on both sapphire and mica substrates using the Chemical Vapor Deposition (CVD) method. The research focuses on optimizing the growth conditions in order to achieve reproducible results and explore the potential of conventional and Van der Waals epitaxy for synthesizing nanolayers and nanoclusters of transition metal dichalcogenides. By carefully selecting appropriately oriented substrates and performing targeted surface modification, we successfully achieved the desired epitaxial growth. The properties of the obtained structures are thoroughly investigated, with emphasis on their potential applications. This research contributes to the development of scalable and high-quality Transition Metal Dichalcogenide (TMD) growth technique, opening prospects for practical applications in various fields.