Study of dark current blocking layer for BiI3 X-ray detector film

A blocking layer to decrease the dark current of BiI₃ X-ray detector was studied by depositing BiOI film on BiI₃ film. The quality of the BiI₃ film was evaluated by X-ray diffraction and photoluminescence. The carrier transport characteristics were evaluated by Hall measurement. The BiI₃ film was n-type and the BiOI film was p-type. The BiI₃/BiOI film exhibited a rectifying current-voltage characteristics, indicating p-n junction formation between BiI₃ and BiOI films. The dark current decreased by two orders of magnitude in the reverse bias. The effective resistivity increased from 1×10⁹ to 1×10¹¹ Ωcm using the blocking layer. The response time to X-ray pulse was less than 33 ms and the sensitivity value was considered to be promising. A BiI₃- BiOI junction band profile was estimated using the Hall measurement data.