Research And First-principles Calculations On Defects In Two-dimensional MoS₂

Because of the excellent electrical performance,two-dimensional molybdenum disulfide becomes one of the new important semiconductor materials.As the structure of MoS₂ is similar to graphene,it has been studied extensively as an important complementary material of graphene.The electronic structures of two-dimensional MoS₂ can be modulated by using specific defects,such as dislocations and rotational stacking faults.At present,there is few reports about research and calculations on defects of two-dimensional MoS₂.In this work,we analysis high resolution photos of monolayer and bilayer MoS₂ got by spherical aberration correction transmission electron microscopy.In the research of monolayer MoS₂,we observe the photos and find the dislocations and rebuild the structures of dislocations in monolayer MoS₂.For bilayer MoS₂,we demonstrate the coexistence of three rotational stacking faults with three different rotational angles,and we prove that the rotational stacking faults are caused by cracks and dislocations in bilayer MoS₂.The results of first-principles calculations show that rotational stacking faults of different rotational angles change the electronic structures of bilayer MoS₂,produce two new symmetries in their bandgaps and offset crystal momentums.Therefore,employing dislocations and rotational stacking faults is a promising route in defect engineering of two-dimensional MoS₂ to fabricate suitable devices for electronics and optoelectronics.