Efficiency and Forward Voltage of Blue and Green Lateral LEDs with v -shaped Defects and Random Alloy Fluctuation in Quantum Wells
Journal
Physical Review Applied
Journal Volume
17
Journal Issue
1
Date Issued
2022
Author(s)
Abstract
For nitride-based blue and green light-emitting diodes (LEDs), the forward voltage Vfor is larger than expected, especially for green LEDs. This is mainly due to the large barriers to vertical carrier transport caused by the total polarization discontinuity at multiple quantum well and quantum barrier interfaces. The natural random alloy fluctuation in quantum wells has proven to be an important factor reducing Vfor. However, this does not suffice in the case of green LEDs because of their larger polarization-induced barrier. V-shaped defects (V-defects) have been proposed as another key factor in reducing Vfor to allow lateral injection into multiple quantum wells, thus bypassing the multiple energy barriers incurred by vertical transport. In this paper, to model carrier transport in the whole LED, we consider both random-alloy and V-defect effects. A fully two-dimensional drift-diffusion charge-control solver is used to model both effects. The results indicate that the turn-on voltages for blue and green LEDs are both affected by random alloy fluctuations and the V-defect density. For green LEDs, Vfor decreases more due to V-defects, where the smaller polarization barrier at the V-defect sidewall is the major path for lateral carrier injection. Finally, we discuss how the V-defect density and size affects the results. ? 2022 American Physical Society.
Subjects
Carrier transport
Defect density
Light emitting diodes
Polarization
Quantum chemistry
Alloy fluctuation
Blue light
Carriers transport
Defects density
Forward voltage
Green light emitting diodes
Lightemitting diode
Quantum-wells
Random alloy
V-shaped defects
Semiconductor quantum wells
SDGs
Type
journal article