Electronic Raman spectra of shallow acceptors in semi-insulating GaAs

Quantitative Raman Scattering from Acceptors in GaAs

Recent reports have demonstrated the possibility of probing acceptor concentrations in bulk semi-insulating GaAs by electronic Raman scattering using 1.06 μm radiation.1 The inefficiency of detectors in this spectral region severely limits sensitivity, precluding extension to epitaxial layers. We will discuss an approach using both 1.06 μm radiation to photo-neutralize acceptors, and a tunable dye laser to excite Raman scattering. Using a cooled CCD detector, an improvement in detection limit of 104 is realized. Comparison of Raman signals with infrared local mode measurements for samples with carbon concentrations from 1×1014 to 4×1015 cm-3 will be reported. The effect of 1.06 μm power density, dye laser wavelength, dye laser power, and sample fluorescence are included.