瓦级大功率InGaN蓝光LED的光色电特性

封装并测量了瓦级大功率InGaN蓝色发光二极管(LED)在不同正向电流I_F驱动下的光通量、电功率、发光效率、发射光谱和色品坐标等参数的变化。研究表明, 光通量与电功率随I_F的增大呈亚线性增加,而发光效率η则下降。当I_F从50 mA一直增大到450 mA左右时,发射光谱的峰值波长λ_p随I_F的增加发生蓝移,蓝移现象可能与InGaN蓝光LED芯片在较大电流时能带被拉平以及In成分的作用有关。当I_F大于500 mA或800 mA后,λ_p又发生红移,红移现象可能与大电流注入下InGaN蓝光LED芯片产生的热效应以及电子-空穴对辐射复合有关。此外,光谱的半峰全宽(FWHM)产生宽化现象,色坐标x和y值也发生变化。

Watt-level High Power InGaN-based Blue LED Photometric, Chromatric and Electric Characteristics

Watt-level high power InGaN-based blue LEDs were packaged using a traditional packaging method, and their luminous flux, electric power, luminous efficiency, emission spectra and chromaticity coordinates were measured under different forward current (IF) from 50 to 1 000 mA, with a current interval of 50 mA. The results showed that the luminous flux rises sub-linearly, but the luminous efficiency declines with the increase of IF. When the temperature rises with the increase of drive current, the carrier kinetic energy enhances, and then more non-equilibrium electrons diffuse out of the quantum wells, which could result in the decrease of luminous efficiency. The spectrum morphologies and the peak wavelength λp shows a slight blue-shift with the increase of IF from 50 mA to 450 mA, which is related to the influence of In ingredient and the leveled band-gap at a proper high current. The blue-shift values are different between different blue LEDs. However, when IF increases from 500 mA to 800 mA, λp shows a slow red-shift due to the temperature dependence of band-gap energy, and the electron-hole pair recombination luminescence mechanism. In addition, full width at half maximum (FWHM) of the InGaN-based blue LED emission spectra is widened, and the reason was analyzed by the model of configuration coordinate. Moreover, the chromaticity coordinate x, y also changes at the same time.Photometric, chromatric and electric characteristics of blue LEDs make important contributions to chip manufacture and the high power white light LEDs, especially, to the high color rendering warm white LEDs.