Band structures of perovskite-like fluorides for vacuum-ultraviolet-transparent lens materials

In the semiconductor industry, perovskite-like fluorides that have wide band gaps are potential candidates for vacuum-ultraviolet-transparent lens materials in optical lithography steppers. KMgF3 and BaLiF3 single crystals have already been grown, but materials with wider band gaps are desired. To find compositions more effective than KMgF3 and BaLiF3, formed local density approximation (LDA) based ab initio band calculations for perovskite-like fluorides ABF(3), where A and B include an exhaustive list of alkali metals, alkaline-earth metals, and other selected elements. We found that LiBeF3, NaBeF3, KBeF3, and RbMgF3 may have wider indirect band gaps than KMgF3 does. We also found that SrLiF3 may have a wider direct band gap than BaLiF3 does.