Study on Trapped Holes in Ti‐Doped Potassium Dihydrogen Phosphate Crystals

The properties of trapped holes (TH) caused by the defect Ti P in potassium dihydrogen phosphate (KDP) crystals have been studied using density functional theory + U and the bond distortion method. By calculating the trapping energy, spin density, and lattice distortions, it is found that the TH is mainly localized on a single oxygen atom around the Ti dopant. The density of states shows that a defect level appears in the bandgap, clearly separated from the valence band maximum. This defect level will affect the optical properties of KDP crystals. Considering the electron‐phonon coupling, the optical spectrum of the TH is obtained, and the results show that an absorption peaks at 206 nm in the deep‐UV region. These results confirm that TH is related to the UV absorption band.