Structural damage characteristics of MoSe2 nanosheets irradiated by oxygen ions.

• High fluences oxygen-ion irradiation led to the structural degradation and tensile stress in the MoSe 2 nanosheets. • Optical band gap energy E g decreased from 1.495 eV to 1.46 eV. • Some properties can be conserved after irradiation for potential applications. • Ion beam techniques can be used for band gap engineering. Molybdenum diselenide (MoSe 2) is one of the most valuable Two-dimensional transition metal dichalcogenides (TMDs) materials due to their unique and exotic physical properties. Its properties can be easily altered in an irradiation environment and therefore affect the properties of MoSe 2 based devices. In this work, we discussed the effect of oxygen ion irradiation on the structures and optical band gap (E g) of the MoSe 2 continuous nanosheets on sapphire substrates by using complementary characterization techniques. The results show that more lattice disorder and lattice damage induced by high fluences oxygen ion irradiation led to the structural degradation and produced tensile stress in the nanosheets. Average optical absorption rate decreased and E g decreased from 1.495 eV to 1.46 eV. The results will be helpful for understanding the damage study of the MoSe 2 continuous nanosheets with oxygen ion irradiation. [ABSTRACT FROM AUTHOR]