Performance of columnar CsI(Tl) scintillation films prepared on special pre-deposited layers

Abstract

CsI(Tl) scintillation films are widely used for X-ray imaging because their micro-columnar structure can decrease the lateral spreading of scintillating light. But the CsI(Tl) films usually show a disorder structure near the interface of the substrate and film. In this work, CsI(Tl) scintillation films were prepared on the substrates covered by a special pre-deposited CsI layer. This pre-deposited layer shows the morphology of isolated islands with uniform distribution which is caused by solid-state dewetting. The inter-island distance is determined by the initial film thickness. It is found that the columns of the CsI(Tl) films deposited on the pre-deposited layer grew from bottom to the top without disorder. The column diameter is determined by the inter-island distance. The XRD patterns of the films show only [100] preferred orientation which was the same as those of the pre-deposited layers. The performances of the films including light output and spatial resolution have been improved when the films are prepared on this kind of special pre-deposited layers.