Characterizations of electronic and optical properties of Sb-based phase-change material stabilized by alloying Cr

Abstract

The application of monatomic Sb material in the phase-change memory has been greatly compromised due to easy crystallization at room temperature. In this work, we alloy 10 at. % Cr into Sb, so that the crystallization temperature of the amorphous Cr10Sb90 thin film has been raised to above 130 °C and the crystallinity can be controlled by different annealing temperatures. We find that Cr10Sb90 thin films possess relatively large electrical and optical contrasts between the amorphous (a-) and crystalline (c-) states, e.g., the resistance of the a-film decreases by three orders of magnitude after crystallization and the real part of the dielectric function of glass is much larger than that of the crystal in the wavelength range of 300 to 1650 nm. The first-principles simulations reveal that Cr doping leads to a more disordered a-state and the Cr-Sb bonds appear to be stronger than Sb-Sb bonds, which explains the enhanced stability of a-Cr10Sb90. Our findings demonstrate that alloying with Cr is an effective way to improve the stability of phase-change materials in the memory applications without damaging the desired properties of these materials.