Unveiling the growth mechanism of FeSeTe films by pulsed laser deposition technique

Abstract

The superconductivity of FeSeTe films, deposited by the pulsed laser deposition (PLD), is extremely sensitive to the preparation conditions. Hence, it is necessary to study the growth mechanism and reveal the key factors affecting the superconductivity of FeSeTe films. Among all the preparation conditions, the substrate temperature (Ts) is one of the most critical one because it can alter the diffusion and nucleation of deposited atoms, as well as subsequent secondary volatilization. In this study, we prepared a series of FeSeTe films deposited on CaF2 substrates with Ts ranging from 25 ℃ to 700 ℃. It is found that the growth mechanism of the FeSeTe films deposited at different Ts is determined by the competition between crystallization and volatilization, and the Ts can serve as an effective means to regulate the (Se+Te): Fe ratio of the FeSeTe films.The superconductivity of the FeSeTe films is co-modulated by the crystallinity and composition. In addition, the Ts can greatly affect the pinning mechanism of the FeSeTe films by introducing the fine nonstoichiometric particles, local chemical inhomogeneity and planar defects. This work facilitates the further performance improvement and practical applications of FeSeTe superconducting films, and is of reference for the FeSeTe film prepared by other deposition methods.