Non-volatile memory is approaching its fundamental limits with the Si3N4 storage layer, necessitating the use of alternative materials to achieve a higher programming/erasing speed, larger storage window, and better data retention at lower operating voltage. This limitation has restricted the development of the charge-trap memory, but can be addressed by using high-k dielectrics. The paper reviews the doping of nitrogen, titanium, and yttrium on high-k dielectrics as a storage layer by comparing MONOS devices with different storage layers. The results show that nitrogen doping increases the storage window of the Gd2O3 storage layer and improves its charge retention. Titanium doping can increase the charge capture rate of HfO2 storage layer. Yttrium doping increases the storage window of the BaTiO3 storage layer and improves its fatigue characteristics. Parameters such as the dielectric constant, leakage current, and speed of the memory device can be controlled by maintaining a suitable amount of external impurities in the device.
