Hole diffusion profile in a p-p+ silicon homojunction determined by terahertz and midinfrared spectroscopic ellipsometry

Noninvasive optical measurement of hole diffusion profiles in p-p(+) silicon homojunction is reported by ellipsometry in the terahertz (0.2-1.5 THz) and midinfrared (9-50 THz) spectral regions. In the terahertz region a surface-guided wave resonance with transverse-electrical polarization is observed at the boundary of the p-p(+) homojunction, and which is found to be extremely sensitive to the low-doped p-type carrier concentration as well as to the hole diffusion profile within the p-p(+) homojunction. Effective mass approximations allow determination of homojunction hole concentrations as p=2.9x10(15) cm(-3), p(+)=5.6x10(18) cm(-3), and diffusion time constant Dt=7.7x10(-3) mu m(2), in agreement with previous electrical investigations.