NEW METALORGANIC GALLIUM PRECURSORS FOR THE GROWTH OF GAAS AND ALGAAS BY CBE

The use of triethylgallium (TEGa) for the CBE growth of GaAs and AlGaAs leads -to, very significant reductions in unintentional carbon incorporation compared to corresponding layers grown using trimethylgallium (TMGa). However, in a continuing effort to generate even further reductions in impurity levels, the present paper provides the first reported comparison of the tri-isopropylgallium (TIPGa) and tri-tertiarybutylgallium (TTBGa) precursors for CBE growth applications. The use of TTBGa is found to lead to unacceptably low GaAs growth rates, an effect which is attributed to a steric influence on the chemisorption process. In contrast, the TIPGa-grown GaAs layers exhibit very important improvements in electrical and optical properties compared to corresponding TEGa-grown material. Results of initial AlGaAs growth experiments performed using TIPGa are also presented.