Nanoscale effect and amorphous frozen transition of antimony selenide thin films for phase change memory

Abstract

Sb₆₆Se₃₄ (SS) thin films with varying nanoscale dimensions are deposited on SiO₂/Si substrates via magnetron sputtering. The effects of thickness variation on the thermal, electrical, and optical properties of SS thin films are systematically investigated. As the film thickness decreases, the crystallization temperature, electrical activation energy, and ten-year data retention are significantly improved. The results of X-ray diffraction indicate that the addition of film thickness can prompt the crystallization process and increase the grain size. The optical band gap fitted by the reflection spectrum decreases with thickness enhancement. The determined surface topography and root-mean-square roughness for SS films imply a much flatter surface for thinner films. The current–voltage and resistance–voltage data confirm that phase-transition random memory based on a thicker film demonstrates a lower RESET consumption. Moreover, ab initio molecular dynamics is employed to simulate the evolution of the amorphous frozen transition, while a range of additional physical properties, such as structural characteristics and electronic configurations, are systematically explored through density functional theory. Our study not only reveals the performance of films of various scales, which satisfies the demand for ultra-speed, high thermal ability, and low power dissipation phase-change memory, but also helps in controlling the scaling of films to tune the phase-transition features and to gain a better comprehensive performance.