Be doping in GaAs by intermittent AsH 3/TEG supply in an ultra-high vacuum

Abstract

Be-doped p +-GaAs epitaxial thin layers were grown on (0 0 1)-oriented GaAs substrates by intermittent supply of arsine, triethylgallium and Bismethylcyclopentadienyl-beryllium [Be(MeCp) 2] in an ultra-high vacuum at low growth temperature 260–375°C. By changing the gas injection sequences and supply time, the surface stoichiometry before the introduction of impurity precursor is controlled. Heavily Be-doped p +-GaAs grown at 290°C shows high carrier concentration up to 8×10 19 cm −3 with Hall mobility of 42 cm 2 V −1 s −1 at nominal room temperature. It is shown that the incorporation of Be is extremely enhanced when Be(MeCp) 2 is exposed on the gallium-stabilized surface. In view of the surface stoichiometry control, Be doping mechanism is discussed on the basis of rate law of surface chemical reactions.