Low-frequency noise of GaN-based ultraviolet light-emitting diodes.

Low-frequency fluctuations of current and light intensity were measured for different types of ultraviolet (UV) light-emitting diodes (LEDs) with wavelengths from 280 to 375 nm. These UV LEDs are suitable for studying steady-state and time-varying UV fluorescences of biological materials. The correlation coefficient between the current and light intensity fluctuations varies with the LED current and load resistance. This dependence is explained in terms of contributions to the 1/f noise from the active region and from the LED series resistance. The noise level could be reduced by operating the UV LEDs at a certain optimum current level and with large external series resistance. [ABSTRACT FROM AUTHOR]