Raman microprobe study of narrow In_xGa_1-xAs stripes on patterned GaAs(100) substrates

The strain and structural variations across InGaAs ridges (∼1 μm) and valleys (∼3 μm) grown on patterned GaAs(100) substrates are examined via Raman microprobe spectroscopy. High spatial resolution scans across these structures show significant variations in the Raman features (phonon frequency, linewidth, and intensity). Variation in the GaAs-like longitudinal optical mode frequency suggests a large difference in strain found in the InGaAs on top of the 1 μm ridges and in the valleys. Concomitant measurement of phonon linewidth and Ar+ laser-induced heating are also indicative of the same. These results, in conjunction with transmission electron microscope studies, demonstrate that Raman microprobe spectroscopy is a powerful tool for probing patterned semiconductor structures on a microscopic scale.