COMPOSITIONAL RELATION OF GAASXSB1-X AND RELATED-COMPOUNDS IN METALORGANIC CHEMICAL-VAPOR-DEPOSITION USING TBAS AND TMSB AS GROUP-V PRECURSORS

Antimony rich solid composition in metalorganic chemical vapor deposit ion (MOCVD) of GaAsxSb1-x, x < P-tBAs(0)/(P-tBAs(0) + P-TMSb(0)), is g enerally observed in MOCVD growth in a lower-temperature range 400 to low 500 degrees C, in contrast to the arsenic rich solid compositional relation usually observed in growth in the higher-temperature range. A similar relation in InAsxSb1-x is also observed. A growth model for this low-temperature range is proposed, where undecomposed or partiall y decomposed TMSb plays all essential role in the growth. Un-(or parti ally) decomposed TMSb has been assumed to remain at a higher concentra tion on the reaction surface than that evaluated applying a thermal eq uilibrium relation with Sb-4 and to have a high reaction equilibrium c oefficient with Ga and to leave methyl groups on some surface Sb's the reby partly suppressing Ga surface reaction. Our calculated result exp lains essential features of the compositional relation.