Identification of the donor and acceptor states of the bond-centered hydrogen–carbon pair in Si and diluted SiGe alloys

Abstract

The electrical and structural properties of two levels (E90 and H180) in diluted n- and p-type Si1 − xGex alloys (0 ≤ x ≤ 0.070) are investigated by high-resolution Laplace deep level transient spectroscopy measurements and first-principles calculations. By exploiting the presence of Ge atoms close to a substitutional C atom, we show that E90 and H180 belong to the same C–H pair (labeled CH1BC) with H in a bond-centered configuration (C—HBC—Si). The relative energies of the various configurations of the CH pair are calculated, and the complete vibrational spectra in the lowest-energy structures for each charge state are predicted.