Quantum confinement effects in Ge [110] nanowires

The effect of dimensional confinement on quantum levels is investigated for hydrogenated Ge [110] nanowires by ``density-functional-theory pseudopotential'' methods. The energy band dispersion is presented for wires up to 2.80.3em0exnm in diameter. By placing a H₂ molecule in vacuum for reference the bands of the different sized wires are aligned and compared. It is found that for wires with diameters smaller than 30.3em0exnm, confinement strongly affects the shape and energies of the conduction bands. It is found that the energy of the valence-band maximum does not change with diameter once a wire is greater than 2.00.3em0exnm. The valence band maximum scales with diameter D as ∝D^-2.2, and the conduction band scales as ∝D^-0.8.