Abstract:

At present, the approaches to fabricate PdSe₂ thin films mainly focus on mechanical exfoliation and chemical vapor deposition. In this study, we report a simple and efficient method to fabricate PdSe₂ thin films on SiO₂/Si substrates. Firstly, a Pd metal layer was deposited on a SiO₂/Si substrate using magnetron sputtering. Then the PdSe₂ thin film was obtained through selenization of the Pd layer at certain temperatures in a vacuum quartz ampule containing Se powder. According to the cross-sectional high-resolution transmission electron microscopy (HRTEM) image, the as-grown PdSe₂ thin film has an average thickness of about 30 nm. The correlation between selenization temperature and electronic transport properties of PdSe₂ thin films was investigated. PdSe₂ thin films with a hole carrier concentration of ~10¹⁸ cm^-3 and a mobility of ~48.5 cm²·V^-1·s^-1 are realized at a low selenization temperature of 300 ℃. It is worth noting that the mobility obtained by the vacuum selenization is superior to that of the p-type PdSe₂ thin films fabricated by mechanical exfoliation from bulk PdSe₂ single crystals. In addition, a relatively large room-temperature magnetoresistance (MR) of 12% is achieved for the PdSe₂ thin films selenized at 300 ℃. With the increase in the selenization temperature from 300 ℃, mobility and magnetoresistance decrease due to the evaporation of Se element at high temperatures. This work demonstrates that present one-step selenization process is a facile and efficient approach to synthesize PdSe₂ films, which could actually be used to prepare PdSe₂ films in a large scale and may have potential applications for next-generation electronic and magneto-electronic devices.

Key words: noble metal dichalcogenide, selenization, electronic transport property, magnetoresistance