INFLUENCE OF RE(EU, ER, TM) DOPANT ON THE ELECTRONIC STRUCTURE,THE CRYSTAL GEOMETRY AND THE OPTICAL PROPERTIES OF GALLIUMNITRIDE WITH THE DFT METHOD

• Main Author: Dharul Asmawan, Mohammad
• Format: Theses
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/38182
• Institution: Institut Teknologi Bandung

Energy efficiency and renewable energy are interesting topics because of increasing global energy demands. This research was motivated by the issue of lighting energy efficiency, considering that lighting is one of the biggest energy demands. Light emitting diode (LED) continues to be developed to obtain optimal efficiency and color as a source of lighting. Group III-Nitride semiconductors such as GaN were attractive to researchers because of the direct wide band gap. GaN doped by rare earth (RE) has unique optical emission property that is full light emission range. Simulation to study electronic structure, crystal geometry and optical properties of GaN and GaN:RE (Eu,Er,Tm) was carried out in this study. In addition, the magnetic properties were also slightly discussed to complete the material characteristics. Phase/0 program based on density functional theory and pseudopotential was used in this simulation. Beginning with optimization of the GaN wurtzite unitcell structure, which is the most stable structure. Then, the unitcell was expanded to be 2x2x1 supercell and Ga substituted with several RE (Eu, Er, Tm). The calculation results showed a pristine GaN has an energy band gap of 2.61 eV with direct band gap. The spin distribution showed symmetry means that the magnetic moments cancel out. Impurity energy level was found around the Fermi level. Because the Fermi levels were found closer to the valence level means that they belong to a p-type semiconductor. The distribution of spin found not to be symmetrical means that GaN:RE showed magnetic properties. Based on DOS, GaN:RE (Eu,Er,Tm) becomes a magnetic p-type semiconductor materials. The dimension of the RE atoms are larger than Ga atoms. For the consequence, the crystal arrangement expanded. Based on this study, GaN:RE with a lower concentration is recommended as an application in a white LED.