Taiwanese researchers improve InGaN VCSELs
Composition-graded electron blocking layer boosts output power
Researchers from the National Chiao Tung University, the National Changhua University of Education, Advanced Optoelectronic Technology Inc, and the Research center for Applied Science in Taiwan have designed and made an InGaN VCSEL with a composition-graded electron blocking layer (GEBL).
In their study, published in Laser Physics Letters, they been demonstrated that laser output performance is improved by using a GEBL when compared to the typical VCSEL structure of a rectangular electron blocking layer.
The output power obtained at 20kAcm-2 is enhanced by a factor of 3.8 by the successful reduction of threshold current density from 12.6 to 9.2kA cm-2 and the enlarged slope efficiency.
Numerical simulation results also suggest that the improved laser output performances are due mainly to the reduction of electron leakage current and the enhanced hole injection efficiency in the multiple-quantum-well (MQW) active region.
'Design and fabrication of a InGaN vertical-cavity surface-emitting laser with a composition-graded electron-blocking layer' by BC Lin et al, appeared in Laser Phys. Lett. 11 085002 doi:10.1088/1612-2011/11/8/085002