Charge Loss Characteristics of Different Al Contents in a HfAlO Trapping Layer Investigated by Variable Temperature Kelvin Probe Force Microscopy

Kelvin probe force microscopy (KFM) technology is applied to investigate the charge storage and loss characteristics of the HfAlO charge trapping layer with various Al contents. The experimental results demonstrate that with the increase of Al contents in the HfAlO trapping layer, trap density significantly increases. Improvement of data retention characteristic is also observed. Comparing the vertical charge loss and lateral charge spreading of the HfAlO trapping layers, the former plays a major role in the charge loss mechanism. Variable temperature KFM measurement results show that the extracted effective electron trap energy level increases with increasing Al contents in HfAlO trapping layer, which is in accordance with the charge loss characteristics.