CHARACTERIZING PLASMA-EXPOSED IN0.52AL0.48AS SURFACE USING PHOTOREFLECTANCE, RAMAN, AND PHOTOLUMINESCENCE SPECTRA METHOD

We have performed Photoreflectance (PR), Raman Scattering (RS), and Ph otoluminescence (PL) experiments to characterize the In0.52Al0.48As su rface exposed to plasma by a gas mixture of CH4/H-2/Ar, PR spectra ind icate that RTE (plasma) causes defects such as nonradiative recombinat ion centers, scattering centers, and defects leading to the decrease o f signal intensity, broaden line width and red shift of the transition s by increasing the rf power. In the Raman scattering study, RIE cause s defects against InAs-like and AlAs-like LO modes vibration. As the r f power increased, the maximum of two LO modes shifts towards lower fr equency and the Line shape becomes increasing asymmetric. Also, the in tensity degrades gradually by disorder and point defects with increasi ng rf power. The PL transition energies show a red-shift with increasi ng the rf power. In addition, the spectral feature broadens, and the i ntensity decreases with rf power higher than 200 W. The consistence of the PL, PR, and RS results indicate that these three methods can be u sed as sensitive probes to evaluate the near surface damage of the epi layer.