Fig. 5. Regulation of the band structure in semiconductors by defects. (a) Band structures of MoS₂ before and after oxygen incorporation. Reproduced with permission from ref. 63. Copyright 2017, Springer Nature. (b) CT process from VB to E_SS and dopant-related states in Co-doped TiO₂, and from defective states to adsorbed 4-MBA. Reproduced with permission from ref. 90. Copyright 2014, Elsevier. (c) CT processes between 4-MPY and Nd-doped ZnO. Reproduced with permission from ref. 51. Copyright 2020, Springer Nature. (d) Electrical modulation of CT enhancement in GERS by the manipulation of the Fermi level under different types of doping conditions. Reproduced with permission from ref. 91. Copyright 2011, John Wiley and Sons.