Evaluation of border traps and interface traps in HfO2/MoS2 gate stacks by capacitance-voltage analysis

Abstract

Border traps and interface traps in HfO2/few-layer MoS2 top-gate stacks are investigated by C-V characterization. Frequency dependent C-V data shows dispersion in both the depletion and accumulation regions for the MoS2 devices. The border trap density is extracted with a distributed model, and interface traps are analyzed using the high-low frequency and multi-frequency methods. The physical origins of interface traps appear to be caused by impurities/defects in the MoS2 layers, performing as band tail states, while the border traps are associated with the dielectric, likely a consequence of the low-temperature deposition. This work provides a method of using multiple C-V measurements and analysis techniques to analyze the behavior of high-k/TMD gate stacks and deconvolute border traps from interface traps.