Fermi level influence on the adsorption at semiconductor surfaces - ab initio simulations

Abstract

Chemical adsorption of the species at semiconductor surfaces is analyzed showing the existence of the two contributions to adsorption energy: bond creation and charge transfer. It is shown that the energy of quantum surface states is affected by the electric field at the surface, nevertheless the potential contribution of electron and nuclei cancels out. The charge transfer contribution is Fermi level independent for pinned surfaces. Thus for Fermi level pinned at the surface, the adsorption energy is independent on the Fermi energy i.e. the doping in the bulk. The DFT simulations of adsorption of hydrogen at clean GaN(0001) and silicon at SiC(0001) surfaces confirmed independence of adsorption energy on the doping in the bulk. For the Fermi level nonpinned surfaces the charge contribution depends on the position of Fermi level in the bulk. Thus adsorption energy is sensitive to change of the Fermi energy in the bulk, i.e. the doping. The DFT simulations of adsorption of atomic hydrogen at 0.75 ML hydrogen covered GaN(0001) surface confirmed that the adsorption energy may be changed by about 2 eV by the doping change from n- to p-type.

21 pages, 11 figures

References in corpus (2)

• On the nature of Surface States Stark Effect at clean GaN(0001) surface
• Dynamical van der Waals atom -surface interaction

Cited by in corpus (4)

• Foundations of ab initio simulations of electric charges and fields at semiconductor surfaces within slab models
• Adsorption of ammonia at GaN(0001) surface in the mixed ammonia/hydrogen ambient - a summary of ab initio data
• General aspects of the vapor growth of semiconductor crystals - a study based on DFT simulations of the NH3/NH2 covered GaN(0001) surface in hydrogen ambient
• Surface charge induced $s{p}^3$-$s{p}^2$ transformation: new energy optimization universal mechanism of (4x4) reconstruction of stoichiometric GaN(0001) surface