Thickness-dependent carrier transport of PdSefilms grown by plasma-assisted metal selenization.

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