Nonvolatile memory capacitors based on Al2O3 tunneling and HfO2 blocking layers with charge storage in atomic-layer-deposited Pt nanocrystals

Abstract

The growth of Pt nanocrystals (NCs) on Al2O3 surface via atomic layer deposition (ALD) was investigated deeply. A charge trapping memory using Pt NC as charge trapping layer and amorphous ALD Al2O3/HfO2 as the tunneling/blocking layers was fabricated. Pure metallic Pt NC can be formed at the initial growth stage, following the nucleation incubation model. Electrical measurements of p-Si\\Al2O3\\Pt NCs\\HfO2 show a larger memory window of 6.6V at the sweeping gate voltage of ±12V and ∼73% retention property after 105s. Fowler–Nordheim tunneling serves as the dominant tunneling mechanism at the applied gate voltage of 10V. Compared to that of 4.0V with HfO2 blocking layer, control sample with Al2O3 blocking layer shows negligible memory window of 0.3V at ±10V, which is attributed to the smaller electric field intensity in the Al2O3 tunneling layer of stacking structures of p-Si\\Al2O3\\Pt NCs\\Al2O3. ALD Pt NCs with a high density of 1.0×1012/cm2 provides a potential approach to fabricate large area nanocrystals for future ultrahigh density nonvolatile memory applications.