Metal nanocrystal memory with sol–gel derived HfO2 high-κ tunnel oxide

Abstract

An all-solution processed metal–oxide–semiconductor (MOS) capacitor structure containing gold (Au) nanoparticles (NPs) within HfO2 high-κ oxide was fabricated. The ultra-thin (~10nm) HfO2 high-κ tunnel oxide layer was prepared by sol–gel process and showed good electrical properties, which were critical to superior memory property of the MOS structure. Au NPs with particle size of about 3.3nm were synthesized by chemical reduction method and then self-assembled onto HfO2 tunnel oxide. Finally, a Si/HfO2/Au NPs/HfO2 memory structure was constructed after the substrate had been covered with a sol–gel-derived HfO2 control oxide layer (~13nm). By utilizing high-quality HfO2 as tunnel oxide, the MOS structure containing Au NPs showed memory effect even at a low voltage of ±3V. Although its memory window was only 0.8V by a swapping voltage between ±5V, the MOS showed desirable retention characteristics. Therefore, we have fabricated nanocrystal memory device with sol–gel derived HfO2 high-k tunnel oxide which are attractive for low operation voltage non-volatile memory applications.