Enhanced thermally aided memory performance using few-layer ReS 2 transistors

Thermally varying hysteretic gate operation in few-layer ReS 2 and MoS 2 back gate field effect transistors (FETs) is studied and compared for memory applications. Clockwise hysteresis at room temperature and anti-clockwise hysteresis at higher temperature (373 K for ReS 2 and 400 K for MoS 2) are accompanied by step-like jumps in transfer curves for both forward and reverse voltage sweeps. Hence, a step-like conductance (STC) crossover hysteresis between the transfer curves for the two sweeps is observed at high temperature. Furthermore, memory parameters such as the RESET-to-WRITE window and READ window are defined and compared for clockwise hysteresis at low temperature and STC-type hysteresis at high temperature, showing better memory performance for ReS 2 FETs as compared to MoS 2 FETs. Smaller operating temperature and voltage along with larger READ and RESET-to-WRITE windows make ReS 2 FETs a better choice for thermally aided memory applications. Finally, temperature dependent Kelvin probe force microscopy measurements show decreasing (constant) surface potential with increasing temperature for ReS 2 (MoS 2). This indicates less effective intrinsic trapping at high temperature in ReS 2, leading to earlier occurrence of STC-type hysteresis in ReS 2 FETs as compared to MoS 2 FETs with increasing temperature.