Effect of aluminium on the phase change properties of Ge₂Sb₂Te₅ for memory applications
摘要
Ge₂Sb₂Te₅ (GST) is a prominent non-volatile phase change material extensively investigated for phase change random access memory (PCRAM) applications. GST exhibits a phase transition from the amorphous phase to a metastable NaCl-type crystalline structure at approximately 145 °C, and followed by a transition to a stable hexagonal phase at around 220 °C. In this study, we explore the effect of substituting Sb with Al to form Ge2 Sb2-xTe5Alx alloys, with x = 0, 0.1, 0.25, 0.5, and 1.0. The incorporation of Al enhances network connectivity and rigidity, significantly influencing the structural, electrical, and optical properties of the GSTt matrix. In particular, the addition of Al stabilizes the metastable FCC phase and suppresses the FCC to hexagonal transition. The electrical resistivity contrast increased by an order of magnitude compared to pristine GST. Also, the crystalline phase resistivity is higher for the Al added samples compared to the undoped GST. The high contrast in electrical resistivity, increased transition temperature, high thermal stability and data retention make it a promising candidate for next-generation PCRAM devices.