TRANSFERABLE TIGHT-BINDING MODEL FOR SI-H SYSTEMS

We develop a tight-binding molecular-dynamics model for Si-H systems that incorporates relevant physics of charge-transfer and local-environment dependence of atomic interactions. Our model was fitted to silane, and yields electronic levels of disilane in good agreement with experiment and vibrational frequencies that are consistent with the experimental trend for SiHn groups. The model describes well the formation energies and energy surfaces for the different charge states of H in c-Si, including the stability of the bond-centered site for positive and neutral charge states and the stability of the tetrahedral site for negative charge states. The model also describes well the structural and electronic properties of a-Si:H models. The present approach utilizes quantum-mechanical forces, incorporates important electronic effects, and is suitable for studying complex phenomena such as H diffusion and dynamics of c-Si or a-Si:H. © 1994 The American Physical Society.