Raman spectroscopy of sputtered AlN films: E_2(high) biaxial strain dependence

摘要

Sputtered [0001] AlN films with directly measured biaxial strain have been investigated by Raman spectroscopy to determine the strain dependence of the zone-center mode frequencies. The E_2(high) feature near 655 cm~(-1) is found to vary linearly with stress, and we determine the strain derivative of the line as -2.9 ± 0.3 cm~(-1)/GPa, confirming the lowest previously reported derivative and a factor of 2 smaller than the largest. The result is 13% larger than has been predicted by ab initio calculations. The other zone-center lines accessible under normally incident geometry from a c-axis film are shown to be unsuitable as strain gauges.