SELECTIVE GROWTH-MECHANISM OF GAAS IN METALORGANIC MOLECULAR-BEAM EPITAXY

GaAs selective growth mechanism was investigated, based on Ga species behavior using trimethyl gallium (TMG) or triethyl gallium (TEG) as the Ga source. Selective growth, using TMG, was obtained at a substrate temperature as low as 400-degrees-C. In the case of TEG use, the selective growth temperature was above 600-degrees-C. Furthermore, selective Ga deposition on a GaAs substrate with a SiO2 mask was carried out, using only an alkyl Ga source without arsenic. The selective Ga deposition was realized at 350-degrees-C for TMG use and above 500-degrees-C for TEG use. These results show that the Ga species related to TMG is easier to desorb from a SiO2 surface than that related to TEG, and that the desorption temperature for the Ga species is strongly correlative to the selective growth temperature. Consequently, the difference in selective growth temperature may be caused by the desorption rate for the Ga species, originating from the alkyl Ga source. Moreover, the difference in Ga species desorption rates, between GaAs surface and SiO2 surface, will contribute to the selective growth.