RANDOM-BETHE-LATTICE MODEL APPLIED TO THE ELECTRONIC-STRUCTURE OF AMORPHOUS AND LIQUID SILICON

Bethe lattices of arbitrary number of nearest-neighbor atoms and geometrical configurations are defined for the standard sp3s* tight-binding Hamiltonian that gives correctly both valence and conduction bands of crystalline Si. Averaged densities of states are obtained through a well-grounded extension of the coherent-potential approximation to random Bethe lattices with off-diagonal disorder. In that way, a unified picture of the electronic structure of Si in amorphous and liquid phases is obtained. Formation energies of dangling and floating bonds are estimated within Chadis tight-binding scheme. © 1990 The American Physical Society.