High-κ HfO2 Nanocrystal Memory Capacitors Prepared by Phase Separation of Atomic-Layer-Deposited HfO2/Al2O3 Nanomixtures

Physical and electrical characteristics of atomic-layer-deposited high-kappa HfO2 nanocrystals in a p-Si/SiO2/[HfO2/Al2O3]/Al2O3/Pt at elevated temperature (similar to 900 degrees C) have been investigated. Because the phase separation of high-kappa HfO2/Al2O3 nanomixtures after high-temperature (900 degrees C) treatment, the high-kappa HfO2 nanocrystals with an average diameter of 5-10 nm and moderate density of > 1 X 10(11) cm-(2) have been confirmed by both high-resolution transmission electron microscope and X-ray photoelectron spectroscope. The high-kappa HfO2 nanocrystal capacitor shows a large hysteresis memory window of Delta V approximate to 4.2 V and high charge density of 1.1 X 10(13)/cm(2) for the sweeping gate voltage of 10 V/-8 V. due to charge storage in the high-kappa HfO2 nanocrystals, while the as-deposited memory capacitor does not show memory window up to the gate voltage of 10 V. An initial memory window of Delta V approximate to 1.2 V is observed at a small programming voltage of +5V, and a memory window of Delta V approximate to 0.9 V is observed after 10(4) s of retention at 85 degrees C, due to the charge confinement in the layer-by-layer of high-kappa HfO2 nanocrystals. (c) 2009 The Electrochemical Society. [DOI: 10.1149/1.3070660] All rights reserved.