A study on the interface and bulk charge density of AIN films with sputtering pressure

An attempt to correlate deposition-induced effects and the morphological properties with the electrical properties of the aluminum nitride (AlN) films have been made. The AlN film was sputter deposited on silicon while increasing the pressure in steps from 2 x 10(-3) to 8 X 10(-3) mbar. An X-ray diffractogram revealed that the intensity of (0 0 2) orientation increased till 6 x 10(-3) mbar pressure, but it changed to (10 0) orientation of the AlN film at 8 x 10(-3) mbar. The FTIR spectra of the absorption band of the films were observed around 682 cm(-1) and became prominent at 6 x 10(-3) mbar. A decrease in the grain size was seen by SEM images at 8 x 10(-3) mbar. The AFM measurements revealed that the surface roughness varied from 1.56 to 3.24 nm with pressure. It was found that the insulator charge density (Q(in)) increased from 1.4 x 10(11) cm(-2) to 1.3 x 10(12) cm(-2) with increase in pressure. On the other hand, the interface state density (D-it) was found minimum (7.3 x 10(11) eV(-1) cm(-2)) at 6 x 10(-3) mbar. It is found that presence of the Q(in), and D-it are primarily governed by the sputtering pressure of the AlN film. (c) 2006 Elsevier Ltd. All rights reserved.