THE EFFECT OF LAYER NUMBERS AND ATOMIC VACANCY ON THE BAND STRUCTURE AND OPTICAL PROPERTIES OF TWO DIMENSIONAL SEMICONDUCTING MoS2

• Main Author: KURNIAWAN (NIM : 10214028), YUDHI
• Format: Final Project
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/31800
• Institution: Institut Teknologi Bandung

Electronic structure and optical properties of MoS2 by variating the layer number and atomic vacancy are studied by using first principle calculation based on density functional theory. As the result, Eg of MoS2 is increased when the layer number is reduced. Furthermore, the type of Eg changes from indirect (???) to direct (???) in monolayer condition. Valence band and the conduction band of MoS2 for all systems contributed by Mo 4d and S 3p states. Mo 4d plays an important role to change the type of Eg. For sulfur vacancy, the defect state appears ~0.6 eV below the conduction band due to dangling bond that gives an effect to Mo 4d. Oxygen substitution on vacancy site can remove the defect state that appears before. The dielectric constant (?0) and constant refractive index (n0) are reduced when the dimension is reduced. The peaks of the imaginary part of dielectric constant (?2) and the highest peak of plasmonic state shifts to the higher energy level by reducing the dimension. For sulfur vacancy and oxygen substitution, ?0 and n0 become smaller compared to pristine MoS2. Furthermore, ?2 and the highest peak of plasmonic state shifts to a lower energy level. This study shows the important role of reducing the dimension and atomic vacancy on the electronic structure and optical properties of MoS2. This study shows the essentials properties of MoS2 for potential optoelectronic device applications.