Study On Thermal Measurement Techniques Of GaN-based LEDs

Gallium nitride(GaN)-based light emitting diodes(LEDs)have superior photoelectric characteristics and have become the most widely used devices in fields such as displays,indicators,and solid-state lighting.However,with the increase of working temperature,GaN-based LEDs will have reliability problems caused by heat such as performance degradation,reliability degradation,failure rate increase,and shortened life,which limits the further development and application of GaN-based LEDs.Therefore,the study of methods related to thermal measurement is of great significance to improve thermal reliability.Given this,the paper systematically studies the key thermal measurement techniques of GaN-based LEDs,including junction temperature,transient thermal,and thermal imaging measurement techniques.The specific research content is as follows:1.A measurement technique for accurately measuring the junction temperature of GaN-based LEDs is suggested.The GaN-based LEDs junction temperature measurement system was built,while the results of the pulse current method and the micro test-current method were studied,and the utilizes of the micro test-current method were improved to reduce the measurement error.Then a new optical imaging method was suggested,which is based on the relationship between the LEDs luminous intensity and temperature,and the junction temperature of the device was obtained through luminescence imaging,and the results were consistent with the improved micro test-current method.By comparing the reliability of the results of different methods,it is proved that the optical method is suitable for actual production and widespread use,and can further obtain the temperature distribution of the surface of the LEDs,which helps to prepare high-performance LEDs.2.The transient thermal characteristics of GaN-based LEDs were measured.First of all,the significance and uses of the structural function in the transient thermal measurement are elaborated;then the effect of different heating conditions on the transient thermal measurement is studied using the transient measurement system: in order to obtain more accurate transient thermal measurement results,different heating currents and heating times are used to study the change of the junction temperature of the LEDs with time,and the heating conditions are determined to have a certain impact on the transient thermal measurement by analyzing the differences in the heat conduction curve;finally,based on the structure functions,the principle of the transient dual interface measurement method is expounded.This method is applied to measure the junction-junction thermal resistance of the device,analyzes the conduction path of the heat flow over time,and introduces the uses of the transient dual interface measurement method in actual production.3.A new measurement method for high-resolution GaN-based LEDs thermal imaging is suggested.First of all,the principles of traditional thermal imaging technics are detailed,including infrared thermal imaging technology and reflective photothermal imaging technology.Respectively,their advantages and disadvantages are pointed out.In addition,based on the previous phenomenon that the LEDs luminous intensity decreased with the increase of temperature,a new method based on the emission of light GaN-based LEDs thermal imaging measurement method is suggested,and the implementation and optimization of the algorithm were studied,including algorithms such as image geometric position correction and pseudo-color enhancement.It takes appropriate using value.