Phase change materials have gained significant interest for the development of high-speed non-volatile electronic memory; however the dependence of electrical switching properties on the material composition for improved device performance is poorly understood. Here, we report an exhaustive experimental analysis on electrical conduction in sub-threshold regime and threshold switching characteristics of Ge1Sb2Te4, Ge2Sb2Te5 and Ge8Sb2Te11 phase change memory (PCM) devices. Thereby, a correlation between material composition and the relevant change in device properties is described. The study of sub-threshold conduction in these devices reveals that the electrical conductivity in the amorphous state decreases upon increasing GeTe content in the (GeTe)x-(Sb2Te3)1-x tie-line leading to better stability of the amorphous state. Moreover, the threshold switching characteristics of these materials demonstrate that upon reducing the GeTe content in (GeTe)x-(Sb2Te3)1-x tie-line, the threshold voltage is reduced and thereby, low power switching of PCM device is achieved. These experimental findings therefore, allow the choice of material composition that enables the interplay between threshold switching characteristics and crystallization speed of active material in the GeSbTe family to tailor the property portfolio suitable for the development of low power, high-speed, non-volatile PCM devices for future computing. © 2019 IOP Publishing Ltd.