Investigation of the surface states in heavily doped GaAs by kelvin probe

The gallium arsenide epitaxial layer work function dependence upon the degree of donor doping is investigated. It is found that the surface aceptor centres of energy Ec – 0.68 eV and density of ≈ 1.4 × 1012 cm−2 become fully occupied by electrons with the increase of free electron concentration in the bulk GaAs above ≈ 2 × 1017 cm−3. Consequently, the Fermi level is no longer pinned by the surface states but shifts to the bottom of the conduction band. Conventiaonal gallium arsenide surface treatment techniques is found to lead to the formation of surface centres of energy Ec – 0.56 eV and concentration above 1.2 × 1013 cm−2. [Russian Text Ignored]