Cubic-phase zirconia nano-island growth using atomic layer deposition and application in low-power charge-trapping nonvolatile-memory devices
Institute of Physics Publishing Ltd.
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The manipulation of matter at the nanoscale enables the generation of properties in a material that would otherwise be challenging or impossible to realize in the bulk state. Here, we demonstrate growth of zirconia nano-islands using atomic layer deposition on different substrate terminations. Transmission electron microscopy and Raman measurements indicate that the nano-islands consist of nano-crystallites of the cubic-crystalline phase, which results in a higher dielectric constant (κ ∼ 35) than the amorphous phase case (κ ∼ 20). X-ray photoelectron spectroscopy measurements show that a deep quantum well is formed in the Al2O3/ZrO2/Al2O3 system, which is substantially different to that in the bulk state of zirconia and is more favorable for memory application. Finally, a memory device with a ZrO2 nano-island charge-trapping layer is fabricated, and a wide memory window of 4.5 V is obtained at a low programming voltage of 5 V due to the large dielectric constant of the islands in addition to excellent endurance and retention characteristics.
KeywordsAtomic layer deposition
Atomic layer deposition
Data storage equipment
High resolution transmission electron microscopy
Semiconductor quantum wells
Transmission electron microscopy
Charge trapping layers
Large dielectric constant
Nonvolatile memory devices
X ray photoelectron spectroscopy