Thickness-dependent carrier transport of PdSe 2 films grown by plasma-assisted metal selenization.

Atomically thin narrow-bandgap layered PdSe 2 has attracted much attention due to its rich and unique electrical properties. For silicon-compatible device integration, direct wafer-scale preparation of high-quality PdSe 2 thin film on a silicon substrate is highly desired. Here, we present the low-temperature synthesis of large-area polycrystalline PdSe 2 films grown on SiO 2 /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 PdSe 2-x phase and eventually to PdSe 2 . The field-effect transistors fabricated from these ultrathin PdSe 2 films exhibit strong thickness-dependent transport behaviors. For thinner films (4.5 nm), a record high on/off ratio of 10 4 was obtained. While for thick ones (11 nm), the maximum hole mobility is about 0.93 cm 2 V -1 S-1, which is the record high value ever reported for polycrystalline films. These findings suggest that our low-temperature-metal-selenized PdSe 2 films have high quality and show great potential for applications in electrical devices.