Current-transport properties of atomic-layer-deposited ultrathin Al2O3

H. C. Lin, Birck Nanotechnology Center and School of Electrical and Computer Engineering, Purdue University,
P. D. Ye, Birck Nanotechnology Center and School of Electrical and Computer Engineering, Purdue University
G. D. Wilk, ASM America

Abstract

We report detailed current-transport studies of ultrathin Al2O3 dielectrics on GaAs grown by atomic layer deposition (ALD) as a function of film thickness, ambient temperature and electric field. The leakage current in ultrathin Al2O3 on GaAs is comparable to or even lower than that of the state-of-the-art SiO2 on Si, not counting on high dielectric constant for Al2O3. By measuring leakage cur- rent at a wide range of temperatures from 133 K to 475 K, we are able to identify the electron transport mechanism and measure the thermal-activation energy of the ultrathin oxide films. This thermal-activation energy is proposed as a parameter to generally character- ize the quality of ultrathin dielectrics on semiconductors.