Lifetime Tests and Junction-Temperature Measurement of InGaN Light-Emitting Diodes Using Patterned Sapphire Substrates

Tsai, Peng-Chi; Chuang, Ricky W.; Su, Y. K.

doi:10.1109/jlt.2006.888234

Cited by 29 publications

(21 citation statements)

References 11 publications

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“…5 And, the enhancement in the internal quantum efficiency benefits from the reduction of threading dislocations by possible lateral growth of GaN epilayer on the patternedsapphire substrate. 5,[10][11][12][13] Numerous patterning features produced on the patternedsapphire substrate by either dry etching or wet etching processes, which includes circle cavities, square cavities, hemispheric bumps, and trenched stripes, have been studied. 5,[14][15][16] Yet, no matter what etching process is used to create the patterns, a hard mask lithographic process is required on the flat c-plane sapphire wafer.…”

Section: Introductionmentioning

confidence: 99%

Characterization study of GaN-based epitaxial layer and light-emitting diode on nature-patterned sapphire substrate

et al. 2012

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Chemical wet etching on c-plane sapphire wafers by three etching solutions (H 3 PO 4 , H 2 SO 4 , and H 3 PO 4 /H 2 SO 4 mixing solution) was studied. Among these etching agents, the mixing H 3 PO 4 /H 2 SO 4 solution has the fastest etching rate (1.5 lm/min). Interestingly, we found that H 2 SO 4 does not etch the c-plane sapphire wafer in thickness; instead, a facet pyramidal pattern is formed on the c-plane sapphire wafer. GaN light-emitting diode (LED) epitaxial structure was grown on the sapphire wafer with the pyramidal pattern and the standard flat sapphire wafer. X-ray diffraction and photoluminescence measurement show that the pyramidal pattern on the sapphire wafer improved crystalline quality but augmented the compressive stress level in the GaN LED epilayer. The horizontal LED chips fabricated on the pyramidal-patterned sapphire wafer have a larger light output than the horizontal LED chips fabricated on the standard flat sapphire wafer by 20%.

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Section: Introductionmentioning

confidence: 99%

Characterization study of GaN-based epitaxial layer and light-emitting diode on nature-patterned sapphire substrate

et al. 2012

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“…Non-radiative recombination induced the generation of heat and increased the junction temperature of the devices. An increase in junction temperature may have changed the encapsulated material from transparent to yellow [17,18]. The electrical characteristics and EMMI images revealed degradations at various junction temperatures.…”

Section: Resultsmentioning

confidence: 99%

Failure and degradation mechanisms of high-power white light emitting diodes

Yang

Lin

Wang

et al. 2010

Microelectronics Reliability

103

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“…However, owing to the chip encapsulation, it is impossible to determine the junction temperature in commercial LED packages directly without special designs [13]. In order to investigate the thermal properties of LED chips, several experimental investigations have been proposed to measure the junction temperature, such as the power output method (POM) [14], the wavelengthshift method (WSM) [15], and the ETM [16], which measures the thermal resistance of LED on the basis of negative correlation relationship between the forward voltage and the junction temperature. Among these three methods, the ETM not only showed great accuracy, but also was much easier to set up and operation.…”

Section: Nondestructive Methodologymentioning

confidence: 99%

Thermal Stability of High-Power LEDs Analyzed With Efficient Nondestructive Methodology

Lee

Chou

Tseng

2013

IEEE Trans. Device Mater. Relib.

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With the continuing advancement in light-emitting efficiency of high-power light-emitting diodes (LEDs), a nondestructive evaluation on thermal reliability, especially regarding the operating temperature and thermal resistance, which directly affect their lifetime and luminous characteristics, is needed. In this paper, we develop a methodology of using a 3-D numerical simulation for transient thermal-conduction analysis, which is combined with the electrical test method to evaluate the junction temperature of a variety of LEDs. As a result, the simulated temperature for LEDs was found to increase with time, whereas the slug temperature showed the same trend for the simulation and the experiment. The measured results indicate that the thermal resistance of AlGaInP-material-based red and amber LEDs reveals higher variability than that of InGaN-material-based white and green LEDs. Via the luminous flux experiment, we have found that the thermal resistance of the LEDs is not the major determination factor of their luminous flux decay. In contrast, the luminous flux decay of the LED is dependent on the chip material being used. Notably, the slug temperature, observed from the pulsed-driven experiment, of the LED appeared to be lower than that observed in the normal steady operation. It is demonstrated that the lifetime and reliability of high-power LEDs can be improved by decreasing the junction and slug temperatures of the devices. This is important as the slug temperature can be controlled by external cooling techniques. In practice, the developed methodology is not restricted to analyze particular LED packaging forms and can be used to investigate various kinds of multichip LED modules as well.

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Lifetime Tests and Junction-Temperature Measurement of InGaN Light-Emitting Diodes Using Patterned Sapphire Substrates

Cited by 29 publications

References 11 publications

Characterization study of GaN-based epitaxial layer and light-emitting diode on nature-patterned sapphire substrate

Characterization study of GaN-based epitaxial layer and light-emitting diode on nature-patterned sapphire substrate

Failure and degradation mechanisms of high-power white light emitting diodes

Thermal Stability of High-Power LEDs Analyzed With Efficient Nondestructive Methodology

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