Abstract
In this dissertation, the fabrication of an artificial structure “Quantum Structure Lattice” (QSL) and its optical properties have been investigated. The QSL consists of a two dimensional orthogonal array of artificial structures with a pitch matches with the Bragg diffraction condition such that it can be used to control the surface emission. The numerical analysis technique based on “finite-difference time-domain (FDTD)” is used to explore the propagation behavior of electromagnetic waves in these sub-wavelength structures. By calculating the optical band structure, the eigenvalue can be found at the boundary of the periodic structure in the reciprocal lattice. After that, the resonant wavelength of QSL is analyzed by the quality factor simulation. Finally, the collimation effect is demonstrated by simulation at the resonant wavelength. In this study, a soft nanoimprint (soft-NIL) technique is employed to fabricate QSL in InGaN/GaN single quantum well (SQW) structures. The soft-NIL uses a polymer mold to transfer nanoscale pattern to the targeted substrate, where the soft mold is made from an anti-sticking coated Si master. In photoluminescence (PL) measurement of multiple layer heterostructures, numerous interference peaks are observed due to multiple reflections between planar interfaces, which make the interpretation of the PL spectrum difficult. A semi-empirical approach is developed. A correction cosine function is generated by judging positions of interference peaks of the PL spectrum to eliminate multiple reflections of planar multiple layered films. Finally, QSL is successfully demonstrated in InGaN/GaN SQWs. The experiment results are verified by FDTD simulations. Some improvements of pattern design and the possibility of optoelectronic device applications are discussed.