RESUMO
In this paper, we report the synthesis of high-quality Ta2Ni3Se8crystals free of noble or toxic elements and the fabrication and testing of photodetectors on the wire samples. A broadband photoresponse from 405 nm to 1550 nm is observed, along with performance parameters including relatively high photoresponsivity (10 mA W-1) and specific detectivity (3.5 × 107Jones) and comparably short response time (τrise= 433 ms,τdecay= 372 ms) for 1064 nm, 0.5 V bias and 1.352 mW mm-2. Through extensive measurement and analysis, it is determined that the dominant mechanism for photocurrent generation is the photo-bolometric effect, which is believed to be responsible for the very broad spectral detection capability. More importantly, the pronounced response to 1310 nm and 1550 nm wavelengths manifests its promising applications in optical communications. Considering the quasi-one-dimensional structure with layered texture, the potential to build nanodevices on Ta2Ni3Se8makes it even more important in future electronic and optoelectronic applications.
RESUMO
Schottky junctions, formed by high work function metals and semiconductors, are important devices in electronics and optoelectronics. The metal deposition in traditional Schottky interfaces usually damages the semiconductor surface and causes defect states, which reduces the Schottky barrier height and device performance. This can be avoided in the atomically smooth interface formed by two-dimensional (2D) metals and semiconductors. For better interface tailoring engineering, it is particularly important to understand various interface effects in such 2D Schottky devices under critical or boundary conditions. Here we report the fabrication and testing of three types of MoS2devices, i.e., using PtTe2, Cr and Au as contact materials. While the Cr/MoS2contact is an ohmic contact, the other two are Schottky contacts. The van-der-Waals interface of PtTe2-MoS2results in a well-defined OFF state and a significant rectification ratio of 104. This parameter, together with an ideality factor 2.1, outperforms the device based on evaporated Au. Moreover, a device in the intermediate condition is also presented. An abrupt increase in the reverse current is observed and understood based on the enhanced tunneling current. Our work manifests the essential role of doping concentration and provides another example for 2D Schottky interface design.
RESUMO
Two-dimensional (2D) materials attached with flexible substrates enable possibilities to apply their superior properties to the rapidly increasing demand for foldable displays and wearable biosensors in the internet-of-things technology. However, previous two-step strategy to construct the flexible devices, namely first obtaining 2D materials elsewhere and then transferring them onto flexible substrates, can cause huge problems, including irreversibly undermining the device performance and limiting the material size. Here we propose a new one-step strategy (other than the liquid phase processing and low temperature synthesis methods), namely directly depositing appropriate 2D materials onto flexible substrates, which involves no transferring and can maintain the crystal quality and properties to the greatest extent. More importantly, this strategy in principle has no limit in the film size, hence removing a main obstacle for the practical use of flexible films, such as complex logic operations and large-area optoelectronic applications. Using this strategy, a centimeter-scale SnSe2film is directly grown on polydimethylsiloxane, which is characterized as a uniform, out-of-plane oriented and semiconducting film that is robust to deformations. Based on the film, a flexible photodetector is fabricated and distinct photoresponse to a broad spectrum of light (405-830 nm) is observed, with remarkable technical parameters.
