Quantitative analysis of doping profile on beveled p-type GaAs structures by micro-Raman spectroscopy

Micro-Raman spectra taken from beveled p-GaAs samples covering a range of concentrations (1×1018–2×1019 cm−3) have been studied. This study concentrated on the evaluation of the changes of Raman intensities measured in frequency positions of transversal optical and longitudinal optical phonons along the bevel. These changes are dependent on doping concentration and due to this fact we have extracted a calibration function, which will be used to determine the doping concentration in nanometer-thin layers. There are two physical values, which was derived from this study: width of surface-depletion layer and width of space-charge layer. Good correspondence between experimental results and theoretical calculations is the proof of correctness of the model of explanation of the changes of micro-Raman and their analysis. The chemical procedure for preparation of homogeneous oxide-free bevel-shaped p-type GaAs structures with small angle was also developed.