Device self‐heating effects in deep UV LEDs studied by systematic variation in pulsed current injection

SET, Inc. 280nm LEDs were studied under various DC and pulse conditions to demonstrate the impact of self‐heating associated with non‐radiative recombination on the output power and lifetime of the devices. A reduction in output power occurs as the pulse width and duty cycle are increased. For 1μsec pulse width the output power at saturation current decreases from 30mW to 4mW as the duty cycle is increased from 1% to 50%, while for 100μsec pulse width, the output power at saturation current decreases from 10 mW to 3.5 mW for the same range of duty cycle. In both cases, the output power at 50% duty cycle approaches that of the DC conditions, indicating that self‐heating has a significant impact on the device performance. Lifetime testing at 100mA was performed under DC and pulse conditions of 100μsec and 1% duty cycle, with half‐lives of 20 hours and 1400 hours, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)