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Direct bandgap opening in sodium-doped antimonene quantum dots: an emerging 2D semiconductor
摘要： Antimonene, which is similar to two-dimensional (2D) phosphorene, has recently gained considerable attention because of its thickness-dependent energy band structure. However, unlike phosphorene, undoped antimonene has an indirect bandgap only at the monolayer limit. In this work, an electrochemical sodium doping strategy was proposed to tune the energy band structure of antimonene. First-principles calculations indicated that a direct bandgap of 0.88 eV formed in 5.55% Na-doped antimonene, while undoped antimonene had an indirect bandgap of 2.38 eV. Optical and electrical measurements provided clear evidence for such a reconstruction of the energy band. We experimentally demonstrated p-type conduction in antimonene quantum dots (QDs)-based field-effect transistors. Furthermore, the induced direct bandgap enabled electric-field control of the surface-enhanced Raman scattering on plasmonic-free antimonene QDs. This allowed for detection of Rhodamine 6G with a detection limit down to the sub-femtomolar level. Our study highlights the potential of doped antimonene as an emerging 2D semiconductor.
关键词： Direct Bandgap,Quantum Dots,Antimonene,Field-Effect Transistors,Surface-Enhanced Raman Scattering,Sodium Doping
更新于2025-09-19 17:13:59
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Laser annealing towards high-performance monolayer MoS2 and WSe2 field effect transistors
摘要： The transition metal dichalcogenides (TMDCs) have been intensively investigated as one of promising nanoelectronic and optoelectronic materials. However, the pervasive adsorbates on the surface of monolayer TMDCs, including oxygen and water molecules from the ambient environments, predominately degrade the device performance, thus hindering the precise applications. In this work, we report the effect of laser irradiation on the transport and photoresponse of monolayer MoS2 and WSe2 devices, and this laser annealing process is demonstrated as one straightforward approach to remove the physically adsorbed contaminations. Compared with vacuum pumping and in-situ thermal annealing treatments, the field-effect transistors after the laser annealing show more than one order of magnitude higher on-state current, and no apparent degradation of device performance at low temperature. The mobility of monolayer WSe2 devices can be enhanced by 3-4 times, and for single-layered MoS2 devices with the commonly used SiO2 as the back-gate, the mobility increases by 20 times, reaching 37 cm2 ? V?1 ? s?1. The efficient cleaning effect of the laser annealing is also supported by the reduction of channel and contact resistances revealed by the transmission line experiment. Further, the enhanced photocurrent by a factor of 10 has been obtained in the laser annealed device. These findings pave the way for the high-performance monolayer TMDCs-based electronic and optoelectronic devices with the clean surface and intrinsic properties.
关键词： TMDCs,monolayer MoS2,photoresponse,field-effect transistors,laser annealing,monolayer WSe2
更新于2025-09-19 17:13:59
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Photoresponse of wafer-scale palladium diselenide films prepared by selenization method
摘要： Palladium diselenide (PdSe2) films exhibit a high charge carrier mobility and sensitivity in photodetection. In this work, wafer-scale PdSe2 thin films with controllable thickness have been synthesized by the selenization of Pd films. A PdSe2-based photodetector can detect a broad wavelength ranging from 420 nm to 1200 nm. The responsivity and detectivity can reach 1.96 × 103 A W-1 and 1.72 × 1010 W / Hz1/2 at VSD = 3 V, respectively. The figure of merit of the photodetection are comparable to the mechanically exfoliated PdSe2 based photodetector. This work demonstrated that selenization is a facile method to synthesize PdSe2 films in large scale and the films are promising for broadband photodetection.
关键词： palladium diselenide,field effect transistors,two-dimensional layered material,photodetection
更新于2025-09-16 10:30:52
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Synthesis, characterization and UV photodetector application of Sb-doped ZnO nanowires
摘要： Sb-doped ZnO nanowires with hexagonal wurtzite structures have been synthesized via chemical vapor deposition method, and the main charge state of Sb dopants is Sb5+. The photoluminescence spectra demonstrate the existence of shallow acceptors, SbZn-2VZn complexes in all probability. On the other hand, Sb doping caused more native and impurity donors in Sb-doped ZnO nanowires. Then, field effect transistors of single Sb-doped ZnO nanowire were fabricated and the transport properties shows n-type conductivity. The competition between shallow acceptors and donors, and the influence of Sb valency need to be investigated further to obtain stable Sb-doped p-type ZnO. At last, we have shown the potential application of Sb-doped ZnO nanowires for nanoscale UV photodetector.
关键词： field effect transistors,UV photodetector,Sb-doped ZnO nanowires,photoluminescence,chemical vapor deposition
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - St. Petersburg, Russia (2019.10.17-2019.10.18)] 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - A Method for Increasing the Low-Temperature Stability of Steady-State Behavior and Common-Mode Interference Resistance CJFET Dual-Input-Stages
摘要： An original input differential stage circuit (DS) on complementary junction field-effect transistors (CJFET) is proposed. Their main designated area is low-noise analog ICs for operation at low temperatures, including cryogenic ones. The special circuit design for setting steady-state behavior of the DS and its parametric optimization in the LTspice environment provide a relatively high stability of the CJFet steady-state behavior of the input transistors in a wide temperature range. It is shown that, in this case, the common- mode rejection ratio is increased.
关键词： low-temperature electronics,differential operational amplifier,LTspice environment,differential stage,common-mode rejection ratio,junction field-effect transistors
更新于2025-09-16 10:30:52
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Photo- and electroluminescence features of films and field effect transistors based on inorganic perovskite nanocrystals embedded in a polymer matrix
摘要： The optical and electrical properties of films and field-effect transistors (FETs) based on pure MEH-PPV, neat CsPbBr3 nanocrystals (NCs), and MEH-PPV:CsPbBr3 NCs composites with different contents of CsPbBr3 NCs are investigated. The films were characterized by absorbance, atomic-force microscope and current-voltage characteristics (I-Vs) techniques. Relative PL and EL intensities and PL spectra of the pure MEH-PPV, neat CsPbBr3 NCs and MEH-PPV:CsPbBr3 NCs films were measured at 300 K at various levels of optical and electrical excitation power; these dependencies of the PL and EL intensities turned out to be sublinear and superlinear respectively. FETs based on MEH-PPV:CsPbBr3 NCs (1:1) films exhibit I-Vs at 290 – 100 K a dominant hole transport mechanism. The mobility of charge carriers was determined at 290 K for neat CsPbBr3 NCs (for electrons: 2.7 10-2 cm2/Vs) and MEH-PPV:CsPbBr3 NCs (1:1) (for holes: 9 cm2/Vs). The temperature dependence of the hole mobility μFET(T) of FETs based on MEH-PPV:CsPbBr3 NCs (1:1) films characteristic of the hopping mode. It was found that the superlinearity of the dependence of EL of MEH-PPV:CsPbBr3 NCs LE-FETs at 290 K increases with increasing concentration of CsPbBr3 NCs due to efficient energy transfer between CsPbBr3 NCs and the MEH-PPV polymer matrix, and also because of the probability of electron tunneling through the potential barrier to electrode. It is expected that the obtained MEH-PPV:CsPbBr3 NCs nanocomposite films will be useful for efficient applications in nanotechnology LEDs, FETs and LE-FETs.
关键词： Energy transfer,Field-effect transistors,Semiconducting polymers,Photo- and electroluminescence,Charge carrier mobility,Inorganic perovskite nanocrystals
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Plug-and-Play Generation and Manipulation of Squeezing on Chip
摘要： We propose a novel graphic method to enable the analysis of the field-effect transistor (FET) threshold voltage variation (cid:2)Vth due to random telegraph signals in a percolative channel. First, through technology computer-aided design simulation with no percolation, both a minimum (cid:2)Vth and a critical curve in a mloc ? σloc plot are produced. The former constitutes a statistical distribution far away from the conventional log-normal one. In the latter, mloc and σloc are the mean and the standard deviation, respectively, of a well-known normal variable in Mueller–Schulz’s percolation theory. The critical mloc ? σloc curve divides the plot into the allowed region and the forbidden region and will go down with increasing gate size. Then, (cid:2)Vth contours in the allowed region are graphically created. While applying to existing experimental (cid:2)Vth statistical distributions of SiON- and high-k metal gate (HKMG)-scaled FETs, resulting paired mloc and σloc at high (cid:2)Vth remain intact, regardless of gate size or gate stack type. This means that the underlying percolation patterns resemble each other, due to the same manufacturing process used. However, if these paired mloc and σloc fall in the forbidden region, it is the critical mloc ? σloc curve dominating. Application to bias and temperature instability statistical data in literature is straightforwardly well done.
关键词： percolation,technology computer-aided design (TCAD),Bias and temperature instability (BTI),trap,random telegraph signals (RTSs),field-effect transistors (FETs)
更新于2025-09-16 10:30:52
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Photophysical and electronic properties of bismuth-perovskite shelled lead sulfide quantum dots
摘要： Metal halide perovskite shelled quantum dot solids have recently emerged as an interesting class of solution-processable materials that possess the desirable electronic properties of both quantum dots and perovskites. Recent reports have shown that lead sulfide quantum dots (PbS QDs) with perovskite ligand-shells can be successfully utilized in (opto)electronic devices such as solar cells, photoconductors, and field-effect transistors (FETs), a development attributed to the compatibility of lattice parameters between PbS and certain metal halide perovskites that results in the growth of the perovskite shell on the PbS QDs. Of several possible perovskite combinations used with PbS QDs, bismuth-based variants have been shown to have the lowest lattice mismatch and to display excellent performance in photoconductors. However, they also display photoluminescence (PL), which is highly sensitive to surface defects. In this work, we present an investigation of the transport and optical properties of two types of bismuth-based perovskite (MA3BiI6 and MA3Bi2I9) shelled PbS QDs. Our photophysical study using temperature-dependent PL spectroscopy between 5 and 290 K indicates that the PL efficiency of the reference oleic acid (OA) capped samples is much higher than that of the Bi-shelled ones, which suffer from traps, most likely formed at their surfaces during the phase-transfer ligand exchange process. Nevertheless, the results from electrical measurements on FETs show the successful removal of the native-OA ligands, displaying electron dominated transport with modest mobilities of around 10?3 cm2 [V s]?1 – comparable to the reported values for epitaxial Pb-based shelled samples. These findings advance our understanding of perovskite shelled QD-solids and point to the utility of these Bi-based variants as contenders for photovoltaic and other optoelectronic applications.
关键词： field-effect transistors,bismuth-perovskite,electronic properties,photoluminescence,photophysical properties,lead sulfide quantum dots
更新于2025-09-12 10:27:22
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Functionalized graphene transistor for ultrasensitive detection of carbon quantum dots
摘要： Ubiquitous carbon nanomaterials have great potential for emerging technologies, but they also pose a threat to human health at the end of their lifecycle, especially when they are introduced into waste or ground waters. Graphene field-effect transistors (GFET) and real time in situ confocal Raman microscopy (CRM) were employed to detect a submonolayer of carbon quantum dots (CQDs) in water. An effective GFET channel was formed on exfoliated and chemical vapor deposited (CVD) graphene. The adsorption of CQDs was monitored by measuring conductance changes in GFETs. The graphene channel was functionalized with (3-aminopropyl) triethoxysilane (APTES), which allowed for easy observation of a shift in the charge neutrality point (CNP) when the graphene channel was exposed to CQDs. The affinity of the CQD’s carboxyl terminal groups to the aminofunctionalized channel enabled a highly sensitive CQD detection based on changes in the GFET conductivity. The adsorption of the CQDs induced a positive shift of the CNP with a limit of detection at concentrations of 239 ppm and 62 ppm for the exfoliated and CVD graphene, respectively. A supporting study of graphene functionalization and CQD adsorption was performed by real time in situ CRM, ellipsometry, and ex situ X-ray photoelectron spectroscopy.
关键词： graphene field-effect transistors,carbon quantum dots,confocal Raman microscopy,chemical vapor deposited graphene,aminofunctionalized channel
更新于2025-09-12 10:27:22
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Fast and broadband photoresponse of few-layer GeSe field-effect transistor with direct bandgaps
摘要： Few-to-monolayer germanium selenide, a new Ⅳ-Ⅵ group layered material recently fabricated by mechanical exfoliation and subsequent laser thinning, is promising in very fast and broadband optoelectronic applications for its excellent stability, natural p-type semiconductor, complicated band structures, and inert surface properties. However, large-scale production of such few-layer GeSe devices with superior performance is still in early stages. In this study, field-effect transistors (FETs) made of few-layer GeSe with direct bandgaps are fabricated. Transistor performance with Schottky contact characteristics is measured at room temperature. Field effect mobility of 4 cm2/Vs and drain currents modulated both in hole and electrons are measured. Photoresponse as a function of the illumination wavelength, power, and frequency are characterized. The few-layer GeSe transistor shows photoresponse to the illumination wavelengths from the visible up to 1400 nm, and photoresponse rise (fall) time of 13 μs (19 μs), demonstrating very broadband and fast detection. The ambipolar behavior and the photoresponse characteristics demonstrate great potential of few-layer GeSe for applications in high stability, very fast and broadband of optoelectronic devices.
关键词： broadband photoresponse,photoresponse time,ambipolar behavior,field effect transistors,direct bandgaps,few-layer GeSe
更新于2025-09-12 10:27:22