InPBi exhibits a strong and broad photoluminescence spectrum at room temperature. The broad spectrum originates from the PIn antisite and Bi-related deep levels. This optical property makes InPBi promising for super-luminescent light source for optical coherence tomography system (medical imaging technology). TEM and APT are used to discuss the structural property of InPBi thin films. The results show that Bi atoms distributes quite non-uniform in InPBi thin films. There is a Bi-rich region at the InPBi/InP interface. Besides, there is a Bi-rich nano-wall in (110) face. This distribution of Bi atoms inhabit the carrier recombination processes in relation to PIn antisite deep level. This work provides references for fabricating super-luminescent diodes applied in optical coherence tomography system.