Microstructure and Electrical Properties of Sb_2Te Phase-Change Material

摘要

Phase Change Memory (PCM) has great potential for commercial applications of next generation non-volatile memory (NVM) due to its high operation speed, high endurance and low power consumption. Sb_2Te (ST) is a common phase-change material and has fast crystallization speed, while thermal stability is relatively poor and its crystallization temperature is about 142□. According to the Arrhenius law, the extrapolated failure temperature is about 55°C for ten years. When heated above the crystallization temperature while below the melting point, its structure can be transformed from amorphous phase to hexagonal phase. Due to the growth-dominated crystallization mechanism, the grain size of ST film is large and the diameter of about 300 run is too large compared with Ge_2Sb_2Te_5 (GST), which may deteriorate the device performance. High resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) were employed to study the microstructures and the results indicate that the crystal plane is {110}. In addition, device cells were manufactured and their current-voltage (I-V) and resistance-voltage characteristics were tested, and the results reveal that the threshold voltage (Vth) of ST film is 0.87 V. By researching the basic properties of ST, we can understand its disadvantages and manage to improve its performance by doping or other proper methods. Finally, the improved ST can be a candidate for optical discs and PCM.