Carrier Recombination Dynamics of InGaN/GaN LEDs and Its Applications to the Optimization of uv Generation Efficiency

Abstract

To obtain small size high speed ultraviolet sources, we studied the UV generation process and efficiency of GaN Blue LEDs. The blue and UV emissions follow a 4-level recombination model. Depending on a given pump pulse amplitude the UV to blue generation ratio increases and saturates with the increasing of pump pulse duration. High efficiency, upto 450 μ W UV power at 380 nm, can be obtained from a 1.2 mW blue LED.

Blue light-emitting diode demonstrated as an ultraviolet excitation source for nanosecond phase-modulation fluorescence lifetime measurements

“…This suggests that the doping levels of the device could be adjusted to produce either more UV output, less blue output, or both. Studies on the UV generation, under pulsed operation, with a blue LED from another manufacturer also indicate that UV output depends on dopant levels, 18 although structure is also important. No UV was observed for SQW blue or green LEDs when operated under pulsed operation.…”

“…17 Modeling of the carrier recombination dynamics of the timeresolved output spectra of pulsed LEDs indicates that the UV and blue generation mechanism can be described by a fourlevel system, and suggests that reduced doping levels should increase the UV light generation. 18 We have identified a commercially available blue LED with sufficiently efficient UV light generation to permit mAlevel, rather than A-level, driving currents. This allows the LED to be driven either continuously or modulated, rather than pulsed, while producing UV light.…”