Control of Conduction Polarity of BiOBr Single Crystal via Chemical Potential Modulation Chemical Vapor Deposition

• • p-type 2D BiOBr FETs achieve a hole mobility of 26.28 cm2 V−1 s−1 and on/off ratio >10^4, providing a much-needed high-performance p-type counterpart for CMOS integration where p-type 2D semiconductors are scarce. • • n-type 2D BiOBr FETs exhibit an electron mobility of 59.59 cm2 V−1 s−1, exceeding most reported n-type 2D FETs and enabling high-speed, low-power n-channel devices. • • Conduction polarity is switched solely by modulating oxygen chemical potential during CPMCVD, eliminating extrinsic doping and its associated mobility degradation and interface defect generation. • • DFT calculations identify bismuth vacancies (under high oxygen chemical potential) as the origin of p-type conductivity and oxygen vacancies (under low oxygen chemical potential) as the origin of n-type conductivity, providing a predictive defect-engineering framework.