Schottky barrier

About: Schottky barrier is a research topic. Over the lifetime, 22570 publications have been published within this topic receiving 427746 citations. The topic is also known as: Schottky barrier junction.

High performance n-doped carbon nanotube field-effect transistors

Abstract: We describe a robust technique for the fabrication of high performance vertically scaled n-doped field-effect transistors from large band gap carbon nanotubes. These devices have a tunable threshold voltage in the technologically relevant range (-1.3V < V_th < 0.5V) and can carry up to 5-6 muA of current in the on-state. We achieve such performance by exposure to potassium (K) vapor and device annealing in high vacuum. The treatment has a two-fold effect to: (i) controllably shift V_th toward negative gate biases via bulk doping of the nanotube (up to about 0.6e/nm), and (ii) increase the on-current by 1-2 orders of magnitude. This current enhancement is achieved by lowering external device resistance due to more intimate contact between K metal and doped nanotube channel in addition to potential reduction of the Schottky barrier height at the contact.

Role of Carbon Nanotubes in Dye-Sensitized TiO2-Based Solar Cells

Abstract: Incorporation of low-dimensional carbon nanostructures such as carbon nanotubes (CNTs) and graphene sheets into the semiconductor electrodes is a common approach to improve the charge collection and photovoltaic performance of dye-sensitized solar cells. In this work, we clarify the role of CNTs in the semiconductor electrodes by investigating and comparing the electronic process in the dye-sensitized TiO2-based photovoltaic devices. The results show that the formed CNT–TiO2 Schottky junction plays a crucial role in the photovoltaic characteristics. According to the thermionic emission theory, the variation of the photocurrent over the voltage of the cells strongly depends on the height of the Schottky barrier. When the output voltage is low, the intrinsic one-dimensional carbon nanostructures can facilitate electron transport. With the voltage of the cell increasing, the energy dissipation on the Schottky junction increases dramatically and CNTs gradually lose the role of electron transport channels. At ...

Comprehensive Pyro-Phototronic Effect Enhanced Ultraviolet Detector with ZnO/Ag Schottky Junction

Abstract: As a coupling effect of pyroelectric and photoelectric effect, pyro-phototronic effect has demonstrated an excellent tuning role for fast response p–n junction photodetectors (PDs). Here, a comprehensive pyro-phototronic effect is utilized to design and fabricate a self-powered and flexible ultraviolet PD based on the ZnO/Ag Schottky junction. By using the primary pyroelectric effect, the maximal transient photoresponsivity of the self-powered PDs can reach up to 1.25 mA W−1 for 325 nm illumination, which is improved by 1465% relative to that obtained from the steady-state signal. The relative persistent secondary pyroelectric effect weakens the height of Schottky barrier, leading to a reduction of the steady-state photocurrent with an increase in the power density. When the power density is large enough, the steady-state photocurrent turns into a reverse direction. The corresponding tuning mechanisms of the comprehensive pyro-phototronic effect on transient and steady-state photocurrent are revealed based on the bandgap diagrams. The results may help us to further clarify the mechanism of the pyro-phototronic effect on the photocurrent and also provide a potential way to optimize the performance of self-powered PDs.

Broadband photodetector based on carbon nanotube thin film/single layer graphene Schottky junction.

Abstract: In this study, we present a broadband nano-photodetector based on single-layer graphene (SLG)-carbon nanotube thin film (CNTF) Schottky junction. It was found that the as-fabricated device exhibited obvious sensitivity to a wide range of illumination, with peak sensitivity at 600 and 920 nm. In addition, the SLG-CNTF device had a fast response speed (τr = 68 μs, τf = 78 μs) and good reproducibility in a wide range of switching frequencies (50-5400 Hz). The on-off ratio, responsivity, and detectivity of the device were estimated to be 1 × 102, 209 mAW-1 and 4.87 × 1010 cm Hz1/2 W-1, respectively. What is more, other device parameters including linear performance θ and linear dynamic range (LDR) were calculated to be 0.99 and 58.8 dB, respectively, which were relatively better than other carbon nanotube based devices. The totality of the above study signifies that the present SLG-CNTF Schottky junction broadband nano-photodetector may have promising application in future nano-optoelectronic devices and systems.

Highly sensitive and flexible strain sensors based on vertical zinc oxide nanowire arrays

Abstract: In this paper, a highly sensitive strain sensor with vertically aligned zinc oxide (ZnO) nanowire arrays on polyethylene terephthalate (PET) film was reported. The device fabrication includes conventional photolithography, metallization, and ZnO nanowire growth through a hydrothermal method. I–V characteristics of the device were highly nonlinear due to the Schottky contact between the nanowire and the gold (Au) electrode. The conductivity of the device is significantly tuned by the change of ZnO/Au Schottky barrier that reflects the strain-induced piezoelectric potential. A gauge factor up to 1813 was obtained from this strain senor, which is higher than the previously reported device based on a lateral ZnO microwire. Theoretical analysis of the piezotronic effect shows that the working nanowire with the largest conductivity change dominates the performance of the device. The non-working nanowire has limited adverse effect on the performance, which explains the robust performance of this novel strain sensor. The stability and fast response of the sensor were also investigated. The sensitive and robust strain sensor is expected to find applications in civil, medical, and other fields.