The technological process to achieve high quality oxides on GsAs and AlGaAs is more difficult than to achieve native oxides on silicon due to the lack of stable oxides on GaAs and related compounds. This paper presents technological conditions to a grow large area of native oxides on AlGaAs epilayers, to be used in laser diodes technology. Experimental results from scanning electron microscopy (SEM) and electron dispersion spectroscopy (EDS) measurements reveals the presence of two native oxides forms, namely GaAsO and AlGaAsO on a 430-mu m(2) surface (twice as large a lateral growth than found in the literature). The proposed oxides structures are Ga0.5As0.5O and Al0.1Ga0.4As0.5O2. These oxide forms have dielectric behaviour on an AlGaAs epilayer.