Abstract

The carrier injection efficiency and confinement within the active region play a crucial role in determining the threshold and slope efficiency of GaN-based vertical-cavity surface-emitting lasers (VCSELs). In this study, two types of composition-graded epitaxial structures are proposed: a composition-graded last quantum barrier (LQB) and a composition-graded electron blocking layer (EBL). GaN-based optically pumped VCSELs incorporating these structures exhibit significant improvements over conventional composition-uniform designs, with threshold reductions of 71.1% and 53.2%, respectively. Band structure analysis reveals that these performance improvements are attributed to enhanced electron injection efficiency and improved hole confinement within the active region as well. Furthermore, pulsed lasing operation in electrically injected VCSELs is successfully demonstrated by employing the composition-graded LQB structure. This study systematically validates the effectiveness of the composition-graded LQB and EBL structures in enhancing GaN-based VCSEL performance from both theoretical and experimental perspectives. These findings provide valuable insights for the development of high-performance VCSELs.

Biography

Baoping Zhang received his PhD degree in Applied Physics from University of Tokyo. He is now a professor of Southern University of Science and Technology, and a visiting professor of Xiamen University, China.