Photo-assisted capacitance-voltage characterization of high-quality atomic-layer-deposited Al2O3/GaN metal-oxide-semiconductor structures

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

Abstract

The authors report on an Al2O3 gate oxide deposited on n-type GaN by atomic layer deposition technique. The high-frequency C-V characteristic shows deep-depletion behavior at room temperature due to the wide band gap semiconductor nature of GaN. Systematic photoassisted C-V measurements demonstrate the importance of postdeposition-annealing process which could improve the average interface trap density D-it of (1-2)x10(12)/cm(2) eV on the as-grown films to 7x10(10)/cm(2) eV on the same films after 800 degrees C rapid thermal annealing in a N-2 ambient. The high-frequency C-V technique or Terman technique is also applied to estimate the mid-gap D-it and compare to the results from photoassisted C-V technique.