Current transport and maximum dielectric strength of atomic-layer-deposited ultrathin Al2O3 on GaAs

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

Abstract

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 A ultrathin films and typical Frenkel-Poole emission for 50-60 A 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.