| The electronic, thermodynamic, and structural properties of three semiconducting materials, ZnO, InN, and PbS, at high pressure are investigated utilizing first-principles calculations based on density function theory. The first two systems, ZnO and InN, crystalize as hexagonal structures at ambient conditions and transition to a cubic structure at higher pressures. The last system, PbS, is cubic at ambient conditions, but transitions to an orthorhombic structure at higher pressure. At ambient conditions, these materials are well known semiconductors with vast amount of research and a variety of wide ranging applications in electrical devices. However, there is a lack of understanding of their physical properties at high pressures. In this thesis, an attempt is made to establish an understanding of the fundamental properties of the high-pressure phase of these materials. DFT and Boltzmann transport theory are used to find how pressure-induced phase transitions affect the electronic and heat transport of these materials. From harmonic approximations, a frozen phonon method is used to calculate the phonon frequencies and thermodynamic properties. |
