Improving the Photon-Electron Coupling Efficiency in GaN-Based Square Microdisks

Abstract

In this work, two types of GaN-based square microdisks, which are suspended microdisks and microdisks with a porous bottom layer based on standard blue/green Light-Emitting Diode (LED) structures grown on Si substrates, are studied. At room temperature, resonant emission was observed in the suspended square microdisk, and the porous microdisk achieved optically pumped lasing at a wavelength of 479 nm with a threshold of 4.37 mW. Optical field simulations reveal that the bridges of the suspended microdisk not only facilitate the transport of light from the microdisk into the bridges for directed propagation but also have no impact on the internal light field distribution. On the other hand, the lasing results of the microdisks with the porous bottom layer demonstrate that the presence of the porous layer enables a high degree of photon confinement within the active region. The results from both types of microdisks confirm that the electron-photon coupling efficiency can be significantly enhanced in the square microcavities, and furthermore that the optical signals can be effectively transmitted through the bridges of the suspended microdisks. This work presents a highly promising approach for Si-based optoelectronic integration.