© 2019 Author(s). The influence of growth temperature (Tsub) on the tail states of GaAs1-xBix (0x0.05) was studied via its sub-bandgap absorption and photoluminescence (PL) characteristics. The Urbach energy (E0) was estimated from the spectral response of the photocurrent of pin GaAs1-xBix photodiodes grown at a low Tsub of 360 °C and a high Tsub of 380 °C. The E0 of GaAs1-xBix is greater than that of GaAs. Once Bi atoms are incorporated, the tail states are formed probably due to Bi atom clustering. The E0 of the GaAs1-xBix sample at Tsub = 380 °C was smaller than the E0 of the sample grown at Tsub = 360 °C; therefore, the formation of the tail states was suppressed by a small increase in the Tsub of 20 °C. At a Tsub of 380 °C, the E0 decreases as the GaBi molar fraction increases. The increase in the Bi flux upon an increase in the GaBi molar fraction may enhance the surfactant effect of the Bi atoms, resulting in an enhancement in the migration of adsorbed atoms at Tsub = 380 °C and a reduction in the tail states. The full-width at half-maximum of the PL peak and the characteristic energy of the temperature dependence of the PL peak energy confirmed the same Tsub tendency of the tail states. The small increase in the Tsub of 20 °C suppressed the inhomogeneous incorporation of Bi atoms into GaAs1-xBix, such as an atomic-scale Bi clustering and the formation of tail states.