Publications by authors named "Morteza Monavarian"
Article Synopsis
- Multiphysics processes like recombination dynamics, carrier transport, and internal heating play key roles in causing thermal and efficiency droop in InGaN/GaN LEDs, but a clear method to differentiate these processes has been lacking.
- This study explores thermal and efficiency droop in single-quantum-well InGaN/GaN LEDs by separating factors such as radiative efficiency and carrier transport using a detailed rate equation framework and a temperature-sensitive pulsed-RF measurement technique.
- Findings reveal that high current densities lead to efficiency droop primarily due to strong non-radiative recombination and saturation of radiative rates, with thermal droop caused by carriers shifting from radiative to non-radiative processes at elevated temperatures
Article Synopsis
- A novel nonpolar GaN-based vertical-cavity surface-emitting laser (VCSEL) was developed featuring a nanoporous bottom distributed Bragg reflector (DBR) for improved performance at room temperature under continuous-wave (CW) optical pumping.!
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- The nanoporous design allows for the growth of high-reflectance DBRs while maintaining essential conductivity, crucial for the high efficiency of VCSELs.!
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- The laser operates at a wavelength of 462 nm with a low threshold power density of around 5 kW/cm and displays consistent emission polarization in the a-direction across various locations.!
Article Synopsis
- - The study investigates the carrier dynamics and recombination coefficients in semipolar InGaN/GaN light-emitting diodes (LEDs) that emit at 440 nm and have a high internal quantum efficiency of 93%.
- - By analyzing the differential carrier lifetime across various current densities, the researchers differentiate between radiative and nonradiative recombination processes, enabling them to extract key recombination coefficients (A, B, and C).
- - Results reveal that semipolar LEDs demonstrate a significantly higher A and B coefficient compared to c-plane LEDs, with lower carrier density and Auger recombination coefficient, contributing to better performance and reduced efficiency droop.
