Flip chip technology has been widely adopted in modern power light-emitting diode (LED) fabrications and its output efficiency is closely related to the submount material properties. Here, we present the electrical, optical and thermal properties of flip chip light-emitting diodes mounted on transparent sapphire and borosilicate glass which have shown a higher output luminous flux when compared to the traditional non-transparent mounted LEDs. Exhibiting both better thermal conductivity and good optical transparency, flip chip LEDs with a sapphire submount showed superior performance when compared to the non-transparent silicon submount ones, and also showed better optical performance than the flip chip LEDs mounted on transparent but poor-thermal-conducting glass substrates. The correspondent analysis was carried out using ANSYS 14 to compare the experimental thermal imaging with the simulation results. TracePro software was also used to check the output luminous flux dependency on different LED mounting designs.
This study is focused on the modulation response of resonant-cavity light-emitting diodes (RCLEDs). Platinum (Pt) atoms are diffused into the 660nm RCLED epitaxial layers to increase the concentration of recombination centers and to improve the modulation speed. The RCLED has an AlInGaP multi-quantum-well active layer which was embedded into AlGaAs-distributed Bragg reflectors to form a one-wavelength (1-λ) optical resonator. Afterwards, the deep-level Pt impurity was diffused into the RCLED and an improved average rise time, from 18.07to12.21ns, was obtained. The corresponding modulation frequency can be increased from 19.54to30.21MHz.
The aim of this study is to determine the diffusion coefficient of palladium (Pd) in gallium arsenide under different annealing conditions. The extent of diffusion was characterized using the secondary ion mass spectrometry (SIMS) technique. The temperature-dependent diffusion coefficients of Pd are 8:4 Â 10 À13 , 2:25 Â 10 À12 , and 9:51 Â 10 À12 cm 2 /s, respectively, at temperatures of 400, 550, and 850 C. The Pd diffusion constant and activation energy in GaAs are calculated as 3:54 Â 10 À10 cm 2 /s and 0.35 eV, respectively. This indicates that the major diffusion mechanism of Pd in GaAs is interstitial diffusion.
This study is focused on the temperature characteristics of platinum-diffused AlGaInP resonant-cavity light-emitting diodes (RCLED). The shape of the platinum-diffused AlGaInP RCLED emission spectra and the full width at half maximum (FWHM) of the main electroluminescent (EL) spectra are almost uninfluenced over the measured temperature range of 20 to 100 °C. Therefore, the platinum-diffused devices show a high characteristic temperature, and a small temperature shift in the peak emission wavelength.
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