Multi-quantum wells (MQWs) consisting of 3 or 3.5 pairs of nominally 8.8-nm-thick GaAs layers and 5.6-nmthick GaAs0.97Bi0.03 were grown by molecular beam epitaxy with varying the growth temperature of GaAs layers, TGaAs, and keeping the growth temperature of the GaAsBi layers at 350• C and their Bi compositional structure and optical properties were investigated. Analysis of x-ray diffraction spectra reveals that 67% of the total Bi atoms supplied during growth of a single GaAsBi layer were segregated on the growing surface and were incorporated into the successive GaAs layer at TGaAs = 350• C. The GaAs layers at TGaAs = 450 and 500• C contained 17% of the Bi atoms totally supplied and 50% of them were evaporated. Almost all Bi atoms segregated during growth of GaAsBi evaporated and were not incorporated into the GaAs layer at TGaAs = 550• C or higher. Photoluminescence (PL) spectra at 13 K shows all MQW samples have good optical quality and the MQW sample grown at TGaAs = 550• C shows the longest wavelength emission peak at 1116 nm which is 44 nm longer than the PL wavelength for the MQW grown at TGaAs = 350• C, even though the tremendous reduction of Bi incorporation into the GaAs layer grown at TGaAs = 550• C. The result strongly suggests that GaAsBi/GaAs has the type II band configuration.