Low threshold lasing in Al-decorated GaN microdisk on silicon substrate

Abstract

In spite of the unique advantages of nitride microcavities laser, the optical loss and threshed values are still high in most GaN microdisk laser integrated on silicon substrate. Herein, we fabricated a GaN microdisk cavity pivoted on Si substrate using standard semiconductor process. Al nanoparticles (NPs) with diameter below 100 nm were then decorated on the GaN cavity as surface plasmons (SPs) gain to enhance the lasing performance. SPs coupling properties and photoluminescence (PL) enhancement of Al decorated cavities were studied via excitation power-dependent PL and time-resolved PL measurements. Low optical loss caused by device suspension and SPs coupling induced Purcell Factor enhancement significantly improve the lasing properties. A spontaneous enhancement in PL (by 1.75 folds) along with altered lasing characteristics, including accelerated exciton recombination, reduced lasing threshold value (by 5 folds approximately), slight lasing intensity improvement and redshift of the resonant mode, were observed.