Advanced effective work function model for photo-oxided GaAs and GaSb surfaces

Electronic processes at the oxidized surfaces of III-As and III-Sb semiconductors have been shown to possess a similar nature. In order to reveal this nature, a combined Raman spectroscopy and scanning Kelvin probe microscopy study of the GaAs and GaSb surfaces with both p- and n-type doping was performed. In addition, the thickness and composition of the native oxide was controlled by laser photo-oxidation. The study revealed a unified process for the formation of a group-V elements surface layer during oxidation and photo-oxidation. The oxidation or photo-oxidation conditions determine whether an amorphous or crystalline layer is formed. Kelvin probe microscopy reveals a correlation between surface potential difference and work function in areas with amorphous and crystalline layers. The study of the work function of the p- and n-type samples has enabled the advancement of the effective work function model and the elucidation of the dependence of the work function on the type and level of doping for III-As and III-Sb semiconductors. • Laser photooxidation of III-As and III-Sb semiconductors forms group-V surface layer. •Intensity of laser pumping controls crystal structure of group-V layer. •Difference of work function of amorphous and crystalline group-V layer is around 100 meV. •An effective work function model accounting for group-V layer electronic properties is proposed.