Approach to Single-Mode Dominated Resonant Emission in GaN-Based Square Microdisks on Si**Supported by the National Key R&D Program of China under Grant Nos. 2016YFB0400102 and 2016YFB0400602, the National Natural Science Foundation of China under Grant Nos. 61674076, 61422401, and 51461135002, the Collaborative Innovation Center of Solid State Lighting and Energy-saving Electronics, Open Fund of the State Key Laboratory on Integrated

Abstract

Square microdisks with round corners are fabricated using a standard GaN-based blue LED on Si substrates. Whispering gallery-like modes in the square microdisks are investigated by finite-difference time-domain simulation. The simulation results reveal that the round corners in square microdisks can substantially suppress the number of light propagation paths and further reduce the number of optical modes. A confocal micro-photoluminescence is performed to analyze the optical properties of the square microdisks at room temperature. The single-mode dominant resonant emission is obtained in the square microdisk with corner radius of 1.5 μm.