Electrical and Mechanical Properties Enhancement in Superlattice-Like GaSb/Ge2Sb2Te5 Phase Change Thin Films

A promising phase change materials based on a distinct nanoscale structure called superlattice is applied in lateral phase change memory (PCM) due to comprehensive performances. In this work, superlattice-like structure of [GaSb(x)/Ge2Sb2Te5 (gamma)](n) (x= 6,9,12,18 nm; gamma = 12,18 nm; n = 3,6) thin films is proposed and alternatively deposited with GaSb and Ge2Sb2Te5 (GST) layers by magnetron sputtering method. The experimental results show that [GaSb(x nm)/GST(12 nm)](3) thin films possess higher crystallization temperature and less volume change than that of monolayer GST. Moreover, [GaSb(x)/GST(12)](3) thin films show super-hardness and super-modulus effect. The hardness enhancement mechanism is discussed and the critical thickness of CST layer is calculated as approximate to 18.1 nm, thus the interfaces are coherent without dislocation threading in critical condition. Therefore, the higher thermal stability and increased hardness values reflect great potential in practical application of superlattice-like [GaSb(x)/GST(12)](n) thin films.