R&D: Reduction of Write Current with Improved Thermal Stability in GeSe2 Doped Sb2Te3 Films for Phase Change Memory (PCM) Applications

Journal of Physics D: Applied Physics has published an article written by Nidhi Bhatt, Shahin Parveen, Abdul Whab, and Pumlian munga, Department of Physics, Jamia Millia Islamia (A central university), New Delhi 110025, India.

Abstract: “Chalcogenide alloy-based semiconductors have gained significant attention in recent decades due to its applications in phase change memory (PCM). Sb₂Te₃ has proven to be an alternative to Static and Dynamic Random Access Memory and can be a suitable candidate for commercial memory devices due to their fast switching speed. However, Sb₂Te₃ suffers from low amorphous phase stability and high RESET current, which needs further improvement for high power efficiency. In this work, we have prepared (Sb₂Te₃)_1−x(GeSe₂)_x (x = 0.06, 0.12, 0.18, 0.24, 0.3) films to investigate their PCM properties. The films showed a rise in transition temperature to transform from high resistive amorphous (RESET) to low resistive crystalline (SET) states with doping that leads to significant enhancement in amorphous phase stability. For 30% doping of GeSe₂ in Sb₂Te₃, the data retention temperature increases from 20.2 °C to 84.6 °C, and the resistance contrast also increases from 10² to 10⁵. The rise in electrical resistance with doping in the amorphous as well as crystalline states leads to a drop in threshold current (I_th) from 3.5 to 0.8 mA. This also reduces the RESET and SET currents. By analyzing the samples using finite element method, it was found out that the high resistance materials produce more heat, resulting in a lower write current in an energy efficient PCM device.“