Optical Transitions in Strained Wurtzite GaN Ultrathin Quantum Disk Under Hydrostatic Pressure Effects

Background: Despite the progress realized in low-dimensional semiconductors, significant researches are still required for them before they can be used at a large scale mainly with the recent emergence of the surface states and the engineering of two dimensional nanomaterials. The ultra-thin quantum dots are characterized by thickness on the atomic scale, possess high flexibility and multi-functionality in optoelectronic applications. Recent studies demonstrated the possibility to drive the commonly used low-dimensional semiconductors into topological insulators states by using electrical or strain engineering instead of searching new chemical materials. Hydrostatic pressure is one of the most useful tools with the purpose to modify the optical properties of low dimensional systems. Method: Our approach is performed in the framework of the effective mass theory and adiabatic approximation. The Schrodinger equation is established in Hylleraas coordinates and solved numerically by using the variational method with a robust ten terms-trial wave function. The excitonic binding and photoluminescence energies are determined and discussed as function of hydrostatic pressure and size. Results: In this work we present the exciton binding energy for a confined electron-hole pair in a cylindrical shaped ultra-thin GaN quantum disk under the effects of hydrostatic pressure. Calculations also include the in-plane electron-hole distance, the hydrostatic pressure coefficient of exciton binding energy as a function of the quantum disk-radius, and the effective band gap. Conclusion: The simultaneous effects of hydrostatic pressure and lateral size on both the excitonic binding energy and photoluminescence show that the strain effect can transform a thin quantum disk into a large-gap material like 2D systems. This approach, constitutes an interesting practical interest, it offers an alternative way to the tuning all energy transitions, instead of modifying the size of the quantum dots or searching for new materials.