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We report on the thermal decomposition of uncapped, ultrathin HfO[SUB2] films grown by chemical vapor deposition on SiO[SUB2]/Si(100) substrates. Medium energy ion scattering, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy were used to examine the films after they had been annealed in vacuum to 900-1050°C. Film decomposition is a strong function of the HfO[SUB2] overlayer thickness at a given temperature, but the underlying SiO[SUB2] layer thickness does not significantly affect the thermal stability of the HfO[SUB2] film. Oxygen diffusion in the system was monitored by [SUP16]O/[SUP18]O isotopic labeling methods. Direct evidence of silicide formation is observed upon decomposition. [ABSTRACT FROM AUTHOR]

Current-voltage characteristics have been measured for an ultrathin atomic-layer-deposited Al2O3 on GaAs as a function of film thickness, ambient temperature, and electric field. Current transport measurements indicate direct tunneling for 12–25 Å ultrathin films and typical Frenkel-Poole emission for 50–60 Å thick films. The maximum dielectric strength, which is of considerable importance for metal-oxide-semiconductor device applications, is studied thoroughly in this letter. The square root of the maximum dielectric strength is found to be roughly reversely proportional to the temperature from 500 to 300 K, and becomes constant below 200 K. The enhancement in the dielectric field strength observed from 300 to 200 K for the ultrathin insulating films can be adequately described using classical models. [ABSTRACT FROM AUTHOR]

Atomic-layer deposition (ALD) provides a unique opportunity to integrate high-quality gate dielectrics on III-V compound semiconductors. We report detailed leakage current and breakdown electric-field characteristics of ultrathin Al2O3 dielectrics on GaAs grown by ALD. The leakage current in ultrathin Al2O3 on GaAs is comparable to or even lower than that of state-of-the-art SiO2 on Si, not counting the high-k dielectric properties for Al2O3. A Fowler-Nordheim tunneling analysis on the GaAs/Al2O3 barrier height is also presented. The breakdown electric field of Al2O3 is measured as high as 10 MV/cm as a bulk property. A significant enhancement on breakdown electric field up to 30 MV/cm is observed as the film thickness approaches to 1 nm. [ABSTRACT FROM AUTHOR]