Photothermal ionization spectroscopy for shallow impurities in ultra-pure silicon

We report the comprehensive results obtained in our group and last few years for the shallow impurities in ultrapure silicon by use of photothermal ionization spectroscopy. The new results reported here include the discovery and investigation of new shallow impurity centers in Si, the detection for the compensation of different types of impurities, the accurate determination for the spin-orbit splitting . of valence band for Si, and the phonon duplicates and Fano resonance for the transitions of shallow impurities in Si. In addition it is also shown experimentally that the sensitivity of the photothermal ionization spectroscopy as used for detecting the concentration of shallow donors in Si can reach as high as 10⁸ cm^–3, much higher than that reported in the literatures up to date, and line width for the sharpest spectral lines in the spectrum is about 0.08 cm^–1, that is, 10 eV.