Structure of Si(100)H: Dependence on the H chemical potential

The formation energies and atomic structures of the 21, 11, and 31 H-terminated Si (100) surfaces were determined through first-principles total-energy calculations. The ranges of the H chemical potential (₇) over which these phases are stable and the equilibrium transition levels were determined. The 31 (monohydride + dihydride) phase is found to be stable with respect to separation into the 21 monohydride and 11 dihydride phases. A 11 canted-row dihydride structure is found to be lower in energy than the 11 symmetric dihydride structure.