Raman microprobe analysis of strain induced by patterned dielectric films of GaAlAs structures

Raman spectra from GaAlAs layers with Si
₃
N
₄
stripes obtained with a microprobe are discussed. The spatial resolution of these Raman spectra was smaller than the scale of the microfabricated features. A significant stress-induced shift in the GaAlAs longitudinal optic (LO) phonon frequency has been observed under 3.5 μm wide Si
₃
N
₄
stripes. Rapid thermal annealing reduced the LO phonon frequency shift, and thus the stress, under the Si
₃
N
₄
stripe. A corresponding dramatic change in optical waveguide behavior under the stripe was observed.