Paper TF1-ThM5
Semiconductor Thin Film Metrology using Coherent Acoustic Phonon Spectroscopy

Thursday, November 3, 2011, 9:20 am, Room 109

Here we discuss the use of coherent acoustic phonon spectroscopy as a noninvasive and nondestructive measurement tool for semiconductor thin films. Specifically we emphasize its usefulness in studying the optoelectronic structure of materials with various types of structural defects. We discuss in-depth studies of ion-implanted GaAs, demonstrating that the technique may be used to quantitatively determine depth profiles of lattice disorder. Our optoacoustic measurements are shown to be 2-3 orders of magnitude more sensitive in defect concentration than channeling techniques, and establish a quantitative dependence between the change in optical response and defect concentration between 10¹⁸-10²¹ defects/cm³. Further, we demonstrate the entire range over which the coherent acoustic phonon technique is applicable in defect studies, and show results ranging from no noticeable change in optical response to complete damping of the phonon wave. We also discuss the electronic nature of the CAP response, which can provide insight into the interplay between lattice disorder and electronic structure.