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Physical Review Letters
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Ab initio design of high-k dielectrics: LaxY 1-xAlO3

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Abstract

We use calculations based on density-functional theory in the virtual crystal approximation for the design of high-k dielectrics, which could offer an alternative to silicon dioxide in complementary metal-oxide semiconductor devices. We show that aluminates LaxY1-xAlO3 alloys derived by mixing aluminum oxide with lanthanum and yttrium oxides have unique physical attributes for a possible application as gate dielectrics when stabilized in the rhombohedral perovskite structure, and which are lost in the orthorhombic modification. Stability arguments locate this interesting composition range as 0.2 < x < 0.4. Phase separation in microdomains is shown to have the tendency to further enhance the dielectric constant. We propose this as a novel family of high-k dielectrics deserving experimental exploration. © 2005 The American Physical Society.

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Physical Review Letters

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