Selective Epitaxial Growth of AlGaAs by Atmospheric Pressure –MOCVD Using Diethylgalliumchloride and Diethylaluminiumchloride

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Abstract
Selective epitaxy of AlGaAs was carried out by atmospheric pressure-MOCVD using DEGaCl and DEAlCl. In the case of Al composition of 0 and 0.16, polycrystal deposition on SiO2 masks was drastically suppressed at the growth rate below 0.020 µm/min. Even, in case of high Al composition of 0.43 and 0.73, a high selectivity of the deposition could be realized as long as the growth rate was kept below 0.017 µm/min. The high selectivity of the deposition can be explained by reevaporation of the reactant species in the form of GaCl and AlCl on the masks. Extremely flat surfaces were also obtained for GaAs selective epilayers grown below substrate temperature of 750°C and growth rate of 0.02 µm/min. In case of Al0.16Ga0.84As selective growth, ridge growth appeared in spite of growth conditions of 0.02 µm/min and 730°C. It is proposed that the ridge growth is related with vapor-phase diffusion from mask areas.