Thickness-dependent carrier transport of PdSe₂ films grown by plasma-assisted metal selenization

Abstract

Atomically thin narrow-bandgap layered PdSe2 has attracted much attention due to its rich and unique electrical properties. For silicon-compatible device integration, direct wafer-scale preparation of high-quality PdSe2 thin film on a silicon substrate is highly desired. Here, we present the low-temperature synthesis of large-area polycrystalline PdSe2 films grown on SiO2/Si substrates by plasma-assisted metal selenization and investigate their charge carrier transport behaviors. Raman analysis, depth-dependent X-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy were used to reveal the selenization process. The results indicate a structural evolution from initial Pd to intermediate PdSe2-x phase and eventually to PdSe2. The field-effect transistors fabricated from these ultrathin PdSe2 films exhibit strong thickness-dependent transport behaviors. For thinner films (4.5 nm), a record high on/off ratio of 104 was obtained. While for thick ones (11 nm), the maximum hole mobility is about 0.93 cm2 V-1 S-1, which is the record high value ever reported for polycrystalline films. These findings suggest that our low-temperature-metal-selenized PdSe2 films have high quality and show great potential for applications in electrical devices.

High‐performance piezoresistive sensors based on transfer‐free large‐area PdSe2 films for human motion and health care monitoring

“…Through the plasma‐enhanced selenization process of a sputter‐deposited Pd film, we successfully obtained uniform and continuous large‐area well‐crystallized PdSe 2 films at temperatures as low as 200°C. As previously demonstrated, this plasma‐enhanced selenization provides films with an improved crystalline quality compared with the conventional low pressure chemical vapor deposition at lower temperatures, 36 making it safer to fabricate devices on PI substrates. Utilizing photolithography to prepattern the initial Pd film, we prepared a large‐area patterned PdSe 2 film on a PI foil, as shown in Figure 2A.…”

Gate-Tunable Responsivity of PdSe2 Nanosheet-Based Bolometric Photodetectors for Mid-Infrared Light Detection

“…Two-dimensional (2D) materials have been extensively studied because of their unique electronic and optoelectronic properties. – Their ultrathin nature makes them highly sensitive to external stimuli. , For instance, many semiconducting 2D materials exhibit excellent gate-tunable conductivity, which holds great promise for next-generation electronic and optoelectronic devices. – In particular, the band gap of black phosphorus (BP) can be adjusted by strain, allowing for realization of tunable electroluminescence and infrared photodetection . The monolayer WSe 2 -based photodiodes with tunable photoresponsivity enables ultrafast machine vision in visible spectral range .…”