First-principles investigation of Cs-NF3 co-adsorption on GaAs(100)-β2(2 × 4) surface

摘要: Abstract The mechanism of Cs-NF3 adsorption on the GaAs(1 0 0)-β2(2 × 4) reconstructed surface is investigated by using first-principles method based density functional theory. cases at ten different sites named as D, D′, T2, T2′, T3, T3′, T4, T4′, H and H′ with two opposite vertical directions are simulated. results show that layered direction can remarkably affect properties. Compared NF3-up models, Cs-up models possess lower energy, smaller work function stronger dipole moment. Meanwhile, it found in trench site T4 energy-preferred position for its lowest energy while topmost As-dimer bridge D most unstable highest energy. Besides, hollow achieve maximum drop function. Furthermore, Mulliken charge distribution indicates NF3 molecule gets negatively charged neutrally models. Combined change atomic geometric structure, inferred [Cs+-NF3-] formed only [Cs+-As-] These help to understand co-activation behavior GaAs photocathode.