A DFT study of intrinsic point defects in monolayer MoSe2

This study is a computational investigation of the electronic structure of the eight most-frequently observed intrinsic point-defect configurations in monolayer Molybdenum diselenide (m-MoSe2); analyzed using the Amsterdam Density Functional (ADF) BAND package. Pristine m-MoSe2 is an intrinsic semiconductor with a direct band gap of 1.44 eV. MoSe2 is defect-sensitive due to the similar orbital character of the Valence Band Maximum (VBM) and Conduction Band Minimum (CBM), with deep states induced in the structure by the defects. These states can be attributed solely to the metal d and chalcogen p states, which spring enhanced photoluminescence, making MoSe2 a potential candidate for optoelectronic applications. Band-gap narrowing is proportional to the number of chalcogen vacancies. All defect configurations cause shifting of the Fermi-level, with metal vacancies shifting the semiconducting character of pristine m-MoSe2 to metallic. Only the antisite defect configuration of MoSe2 and Mo-vacancies at a large distance could introduce spin in the structure, with spin attributed to the metal d and chalcogen p states. These findings suggest the possible application of m-MoSe2 for fabricating DMS by defect engineering.