Junction-Temperature Determination in InGaN Light-Emitting Diodes Using Reverse Current Method

2013 ◽  
Vol 60 (1) ◽  
pp. 241-245 ◽  
Author(s):  
Biqing Wu ◽  
Siqi Lin ◽  
Tien-Mo Shih ◽  
Yulin Gao ◽  
Yijun Lu ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Reverse Current ◽  
Current Method ◽  
Junction Temperature ◽  
Light Emitting ◽  
Temperature Determination

Study of temperature sensitive optical parameters and junction temperature determination of light-emitting diodes

2012 ◽  
Vol 100 (20) ◽  
pp. 202108 ◽  
Author(s):  
Yue Lin ◽  
Yu-Lin Gao ◽  
Yi-Jun Lu ◽  
Li-Hong Zhu ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Junction Temperature ◽  
Temperature Sensitive ◽  
Optical Parameters ◽  
Light Emitting ◽  
Temperature Determination

A Technique for the Direct Measurement of the Junction Temperature in Power Light Emitting Diodes

2020 ◽  
pp. 1-1
Author(s):  
Demetrio Iero ◽  
Massimo Merenda ◽  
Sonia Polimeni ◽  
Riccardo Carotenuto ◽  
Francesco G. Della Corte
Keyword(s):  
Direct Measurement ◽  
Light Emitting Diodes ◽  
Junction Temperature ◽  
Light Emitting

scholarly journals Numerical Simulation on Electrical-Thermal Properties of Gallium-Nitride-Based Light-Emitting Diodes Embedded in Board

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Xing-ming Long ◽  
Rui-jin Liao ◽  
Jing Zhou
Keyword(s):  
Finite Element ◽  
Gallium Nitride ◽  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Thermal Characteristics ◽  
Junction Temperature ◽  
Current Crowding ◽  
Total Thermal Resistance ◽  
Light Emitting ◽  
Packaging Structure

The electrical-thermal characteristics of gallium-nitride- (GaN-) based light-emitting diodes (LED), packaged by chips embedded in board (EIB) technology, were investigated using a multiphysics and multiscale finite element code, COMSOL. Three-dimensional (3D) finite element model for packaging structure has been developed and optimized with forward-voltage-based junction temperatures of a 9-chip EIB sample. The sensitivity analysis of the simulation model has been conducted to estimate the current and temperature distribution changes in EIB LED as the blue LED chip (substrate, indium tin oxide (ITO)), packaging structure (bonding wire and chip numbers), and system condition (injection current) changed. This method proved the reliability of simulated results in advance and useful material parameters. Furthermore, the method suggests that the parameter match on Shockley's equation parameters, Rs, nideal, and Is, is a potential method to reduce the current crowding effect for the EIB LED. Junction temperature decreases by approximately 3 K to 10 K can be achieved by substrate thinning, ITO, and wire bonding. The nonlinear-decreasing characteristics of total thermal resistance that decrease with an increase in chip numbers are likely to improve the thermal performance of EIB LED modules.

Study the Effect of Junction Temperature on the Peak Wavelength in GaN-Based High-Power Green Light Emitting Diodes

2011 ◽  
Vol 399-401 ◽  
pp. 1034-1038
Author(s):  
Rong Rong Zhuang ◽  
Ping Cai ◽  
Jiang Li Huang
Keyword(s):  
High Power ◽  
Temperature Rise ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Red Shift ◽  
Junction Temperature ◽  
Spectral Peak ◽  
Peak Wavelength ◽  
Drive Current ◽  
Light Emitting

The junction temperature of GaN-based high-power green light emitting diodes is measured using the temperature coefficients of the diode forward voltage, from changes in temperature and changes in drive current to measure the LED junction temperature and the corresponding spectral, Respectively. Experiments show that, junction temperature due to environmental temperature increased, and the red shift of the spectral peak wavelength. When low temperature or less then the rated current range, the drive current increased in junction temperature rise due to the spectral peak wavelength blue shift . When the current is increased in the range of close to or greater than the rated current, leading to the junction temperature rise will cause spectral red shift . The peak wavelengths’ shift degree of 0.0579nm / k, 0.0751 nm / k and-0.1974nm / k, -0.0915 nm / k are calculated in both cases. The phenomenon is due to the LED junction temperature increases lead to band gap shrinkage, and the result of the role of spontaneous polarization and piezoelectric polarization in Ⅲ-nitride semiconductor materials.

ACCURATE MEASUREMENT OF ULTRAVIOLET LIGHT-EMITTING DIODES

2021 ◽  
Author(s):  
C. Yuqin Zong ◽  
Cameron Miller
Keyword(s):  
Ultraviolet Light ◽  
Light Emitting Diodes ◽  
Luminous Flux ◽  
Junction Temperature ◽  
Integrating Sphere ◽  
Light Emitting ◽  
Type D ◽  
Uv Led ◽  
Uv Leds ◽  
Ultraviolet Light Emitting Diodes

We have developed a new calibration capability for 200 nm to 400 nm ultraviolet light-emitting diodes (UV LEDs) using a Type D gonio-spectroradiometer. The recently-introduced mean differential continuous pulse (M-DCP) method is used to overcome the measurement difficulty associated with the initial forward voltage, VF, anomaly of a UV LED, which makes it impossible to use VF to infer junction temperature, TJ, during pulsed operation. The new measurement facility was validated indirectly by comparing the measured total luminous flux of a white LED with that measured using the NIST’s 2.5 m absolute integrating sphere. The expanded calibration uncertainty for the total radiant flux is approximately 2 % to 3 % (k = 2) depending the wavelength of the UV LED.

Light-emitting diodes as light sources for spectroscopy: Sensitivity to temperature

2017 ◽  
Vol 25 (6) ◽  
pp. 416-422 ◽  
Author(s):  
Clinton J Hayes ◽  
Kerry B Walsh ◽  
Colin V Greensill
Keyword(s):  
Ambient Temperature ◽  
Near Infrared ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Junction Temperature ◽  
Effect Of Temperature ◽  
Light Sources ◽  
Spectral Variation ◽  
Light Emitting ◽  
Full Intensity

Understanding of light-emitting diode lamp behaviour is essential to support the use of these devices as illumination sources in near infrared spectroscopy. Spectral variation in light-emitting diode peak output (680, 700, 720, 735, 760, 780, 850, 880 and 940 nm) was assessed over time from power up and with variation in environmental temperature. Initial light-emitting diode power up to full intensity occurred within a measurement cycle (12 ms), then intensity decreased exponentially over approximately 6 min, a result ascribed to an increase in junction temperature as current is passed through the light-emitting diode. Some light-emitting diodes displayed start-up output characteristics on their first use, indicating the need for a short light-emitting diode ‘burn in’ period, which was less than 24 h in all cases. Increasing the ambient temperature produced a logarithmic decrease in overall intensity of the light-emitting diodes and a linear shift to longer wavelength of the peak emission. This behaviour is consistent with the observed decrease in the IAD Index (absorbance difference between 670 nm and 720 nm, A670–A720) with increased ambient temperature, as measured by an instrument utilising light-emitting diode illumination (DA Meter). Instruments using light-emitting diodes should be designed to avoid or accommodate the effect of temperature. If accommodating temperature, as light-emitting diode manufacturer specifications are broad, characterisation is recommended.

Experimental investigation and empirical modelling of thermal and drive current effect on optical performance of commercial LEDs

2020 ◽  
pp. 147715352097693
Author(s):  
AN Padmasali ◽  
SG Kini
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Operating Conditions ◽  
Junction Temperature ◽  
Optimum Operating ◽  
Current Effect ◽  
Drive Current ◽  
Light Emitting ◽  
Empirical Modelling ◽  
Output Performance

Light-emitting diode is the most dominant lighting technology, and lumen output performance is dependent on junction temperature and operating drive current. An experimental analysis is performed to study the thermal and drive current effect on lumen output, and an empirical model is developed to determine the optimum operating conditions of temperature and drive current so as to obtain a maximum lumen output profile. Three commercially available light-emitting diode down-lighter’s light-emitting diodes are chosen for the study. The investigation reveals that there exists an optimum drive current at which lumen output is maximum, and it has a linear relation with junction temperature. Pulse-soak testing was performed to study the deviations of pulsed and continuous operation of drive current to understand the performance of light-emitting diodes. The work helps light-emitting diode luminaire manufacturers to design a controlled power electronic circuit so as to maximize the lumen output effectively and accurately.

A Continuous Rectangular-Wave Method for Junction Temperature Measurement of Light-Emitting Diodes

2019 ◽  
Vol 34 (11) ◽  
pp. 10414-10424
Author(s):  
Ze-Hui Liu ◽  
Jia-En Huang ◽  
Yu-Lin Gao ◽  
Zi-Quan Guo ◽  
Yue Lin ◽  
...  
Keyword(s):  
Temperature Measurement ◽  
Light Emitting Diodes ◽  
Junction Temperature ◽  
Wave Method ◽  
Light Emitting ◽  
Rectangular Wave
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