Low-voltage and high-performance field-effect transistors based on ZnxSn1-xO nanofibers with a ZrOx dielectric

Electrospun Nanofibers for Integrated Sensing, Storage, and Computing Applications

Electrospun nanofibers have become the most promising building blocks for future high-performance electronic devices because of the advantages of larger specific surface area, higher porosity, more flexibility, and stronger mechanical strength over conventional film-based materials. Moreover, along with the properties of ease of fabrication and cost-effectiveness, a broad range of applications based on nanomaterials by electrospinning have sprung up. In this review, we aim to summarize basic principles, influence factors, and advanced methods of electrospinning to produce hundreds of nanofibers with different structures and arrangements. In addition, electrospun nanofiber based electronics composed of both two-terminal and three-terminal devices and their practical applications are discussed in the fields of sensing, storage, and computing, which give rise to the further integration to realize a comprehensive and brain-like system. Last but not least, the emulation of biological synapses through artificial synaptic transistors and additionally optoelectronics in recent years are included as an important step toward the construction of large-scale, multifunctional systems.

Role of Fluoride Doping in Low-Temperature Combustion-Synthesized ZrOx Dielectric Films

Zirconium oxide (ZrO_x) is an attractive metal oxide dielectric material for low-voltage, optically transparent, and mechanically flexible electronic applications due to the high dielectric constant (κ ∼ 14-30), negligible visible light absorption, and, as a thin film, good mechanical flexibility. In this contribution, we explore the effect of fluoride doping on structure-property-function relationships in low-temperature solution-processed amorphous ZrO_x. Fluoride-doped zirconium oxide (F:ZrO_x) films with a fluoride content between 1.7 and 3.2 in atomic (at) % were synthesized by a combustion synthesis procedure. Irrespective of the fluoride content, grazing incidence X-ray diffraction, atomic-force microscopy, and UV-vis spectroscopy data indicate that all F:ZrO_x films are amorphous, atomically smooth, and transparent in visible light. Impedance spectroscopy measurements reveal that unlike solution-processed fluoride-doped aluminum oxide (F:AlO_x), fluoride doping minimally affects the frequency-dependent capacitance instability of solution-processed F:ZrO_x films. This result can be rationalized by the relatively weak Zr-F versus Zr-O bonds and the large ionic radius of Zr⁺⁴, as corroborated by EXAFS analysis and MD simulations. Nevertheless, the performance of pentacene thin-film transistors (TFTs) with F:ZrO_x gate dielectrics indicates that fluoride incorporation reduces I-V hysteresis in the transfer curves and enhances bias stress stability versus TFTs fabricated with analogous, but undoped ZrO_x films as gate dielectrics, due to reduced trap density.

Low-voltage and fast-response SnO2nanotubes/perovskite heterostructure photodetector

One-dimensional metal-oxides (1D-MO) nanostructure has been regarded as one of the most promising candidates for high-performance photodetectors due to their outstanding electronic properties, low-cost and environmental stability. However, the current bottlenecks are high energy consumption and relatively low sensitivity. Here, Schottky junctions between nanotubes (NTs) and FTO were fabricated by electrospinning SnO₂NTs on FTO glass substrate, and the bias voltage of SnO₂NTs photodetectors was as low as ∼1.76 V, which can effectively reduce energy consumption. Additionally, for improving the response and recovery speed of SnO₂NTs photodetectors, the NTs were covered with organic/inorganic hybrid perovskite. SnO₂NTs/perovskite heterostructure photodetectors exhibit fast response/recovery speed (∼0.075/0.04 s), and a wide optical response range (∼220-800 nm). At the same time, the bias voltage of heterostructure photodetectors was further reduced to 0.42 V. The outstanding performance is mainly attributed to the formation of type-II heterojunctions between SnO₂NTs and perovskite, which can facilitate the separation of photogenerated carriers, as well as Schottky junction between SnO₂NTs and FTO, which reduce the bias voltage. All the results indicate that the rational design of 1D-MO/perovskite heterostructure is a facile and efficient way to achieve high-performance photodetectors.

Modulating electrical and photoelectrical properties of one-step electrospun one-dimensional SnO2 arrays

One-dimensional nanostructured SnO₂ has attracted intense research interest due to its advantageous properties, including a large surface-to-volume ratio, high optical transparency and typical n-type properties. However, how to fabricate high-performance and multifunctional electronic devices based on 1D nanostructured SnO₂ via low-cost and efficient preparation techniques is still a huge challenge. In this work, a low-cost, one-step electrospun technology was employed to synthesize the SnO₂ nanofiber (NF) and nanotube (NT) arrays. The electrical and photoelectrical parameters of SnO₂ NTs-based devices were effectively controlled through simple changes to the amount of Sn in the precursor solution. The optimal 0.2 SnO₂ NTs-based field effect transistors (FETs) with 0.2 g SnCl₂*4H₂O per 5 ml in the precursor solution exhibit a high saturation current (∼9 × 10^-5 A) and a large on/off ratio exceeding 2.4 × 10⁶. Additionally, 0.2 SnO₂ NTs-based FET also exhibit a narrowband deep-UV photodetectivity (240-320 nm), including an ultra-high photocurrent of 307 μA, a high photosensitivity of 2003, responsibility of 214 A W^-1 and detectivity of 2.19 × 10¹³ Jones. Furthermore, the SnO₂ NTs-based transparent photodetectors were as well be integrated with fluorine-doped tin oxide glass and demonstrated a high optical transparency and photosensitivity (∼199). All these results elucidate the significant advantages of these electrospun SnO₂ NTs for next-generation multifunctional electronics and transparent photonics.

Combustion synthesis of electrospun LaInO nanofiber for high-performance field-effect transistors

One-dimensional semiconductor nanofibers are regarded as ideal materials for electronics due to their distinctive morphology and characteristics. In this work, La-doped indium oxide (LaInO) nanofibers are fabricated as the channel layer to reduce O vacancies and the density of interface trap states; this is clearly confirmed by investigating the stability under positive bias stress and the capacitance-voltage for field-effect transistors (FETs). The In₂O₃ nanofiber FETs optimized by doping with 5 mol% La exhibit excellent electrical performance with a mobility of 4.95 cm² V^-1 s^-1 and an on/off current ratio of 1.1 × 10⁸. In order to further enhance the electrical performance of LaInO nanofiber FETs, ZrAlO _x film, which has a high dielectric constant, is employed as the insulator for the LaInO nanofiber FETs. The LaInO nanofiber FETs with ZrAlO _x insulator have a high mobility of 13.5 cm² V^-1 s^-1. These findings clearly indicate the great promise of La-doped In₂O₃ nanofibers in future one-dimensional nanoelectronics.