Phase-change memory (PCM) has considerable promise for new applications based on von Neumann and emerging neuro-morphic computing systems. However, a key challenge in harnessing the advantages of PCM devices is achieving high-speed operation of these devices at elevated temperatures, which is critical for the effi-cient processing and reliable storage of data at full capacity. Herein, we report a novel PCM device based on Ta-doped antimony telluride (Sb2Te), which exhibits both high-speed characteristics and excellent high-temperature characteristics, with an operation speed of 2 ns, endurance of > 106 cycles, and reversible switching at 140 ℃. The high coordination number of Ta and the strong bonds between Ta and Sb/Te atoms contribute to the robustness of the amorphous structure, which improves the thermal stability. Furthermore, the small grains in the three-dimensional limit lead to an increased energy efficiency anda reduced risk of layer segregation, reducing the power consumption and improving the long-term endurance. Our findings for this new Ta–Sb2Te material system can facilitate the development of PCMs with improved performance and novel applications.