Papers by Keyword: Dimer Codopant

Abstract: Electronic structures of silicon with carbon, indium, or indium-carbon dimers were calculated to investigate the interaction between indium and carbon in X center due to the indium-carbon dimers. Ab initio calculations were carried out mainly for basic Si₇₁H₆₀, C-Si₇₀H₆₀, In-Si₇₀H₆₀, and InC-Si₆₉H₆₀ clusters. The results showed that : (i) the X level was observed at E_HOMO + 0.42 eV in the InC-Si₆₉H₆₀ which was a little bit shallower than E_HOMO + 0.44 eV of the corresponding substitutional In in the In-Si₇₀H₆₀, (ii) dominant constituents of density of states of the X level were the partial densities of states of In and Si, and (iii) the X level had the antibonding nature between In and C.

Abstract: It is known that acceptor-carbon complexes have ionization energies less than those of the corresponding substitutional, separate acceptors in silicon. We present the formation mechanism for a shallower acceptor energy level called an X level that is due to an indium- carbon pair. Ab initio calculation methods were used to evaluate electronic structures and lattice relaxations of silicon with indium, carbon or a carbon-indium dimer. The results shows that the bonding interaction between the 5p orbitals of the indium atom and the 3sp orbitals of the silicon atoms bound with the indium atom mainly determines the ionization energy of the X level, and the ionic bonding interaction of the carbon atomic orbitals with the indium atomic orbitals in the X level enables the bonding interaction of the orbitals between the indium atom and the silicon atom to lower the corresponding indium acceptor level, and then to form the shallower X level.