Polarized cathodoluminescence for strain measurement

Strain can alter the properties of semiconductor materials. The selection of a strain measurement technique is a trade-off between sensitivity, resolution, and field of view, among other factors. We introduce a new technique based on the degree of polarization of cathodoluminescence (CL), which has excellent sensitivity (10^-5), an intermediate resolution (about 100 nm), and an adjustable field of view. The strain information provided is complementary to that obtained by CL spectroscopy. Feasibility studies are presented. The experimental setup and the data treatment procedure are described in detail. Current limitations are highlighted. The technique is tested on the cross section of bulk indium phosphide samples strained by a patterned hard mask.