Raman Characterization of Active B-Concentration Profiles in Individual p-Type/Intrinsic and Intrinsic/p-Type Si Nanowires

Active B-concentration profiles of modulation doped p-type/intrinsic (p-i) and intrinsic/p-type (i-p) silicon nanowires (SiNWs) grown by a vapor−liquid−solid process were studied by analyzing Fano-type spectra in Raman spectroscopy. The analysis of Raman spectra of as-grown, annealed, and oxidized p-i and i-p SiNWs revealed that B atoms are mainly doped from the surface by conformal deposition of a heavily doped layer on the side wall of a SiNW. The surface doping results in strong gradient in B concentration along the axial and radial directions.