InGaN/AlGaN LED

FIGURE 2 L-I characteristic of the InGaN/AlGaN LED on sapphire under DC operation at 30°C. The inset shows the ageing result under a constant current density of 60 A/cm2 (30 mA) at 30°C. 

FIGURE 3 Variation of output power from an InGaN/AlGaN LED as a function of ageing time under various injected current densities. Each ageing test was performed for 24 hr at 30°C. 

InGaN/AlGaN LED were determined to be 0.23 eV and 7 hr1 at 100 A/cm2, and 0.25 eV and 270 hr 1 at 200 A/cm2, respectively. Thus, the output power from the InGaN/AlGaN LED decreases during the ageing test under higher injected current densities and ambient temperatures. 

The typical output power and external quantum efficiency of the UV LEDs were 5 mW and 7.5%, which were about five times higher than those of previously reported UV InGaN/ AlGaN DH LEDs at a current of 20 mA [1,13-15], The peak wavelength and the full-width at half-maximum (FWHM) of the emission spectra were 371 nm and 8.6 nm, respectively. The peak wavelength (371 nm) is much shorter than that (400 nm) of previous UV LEDs, which is much better for exciting phosphors. 

Figure 25 shows the structure of InGaN/AlGaN DH LEDs (14-17). As a buffer layer, GaN was used instead of AIN. For cladding layers of DH structure, AIo.isGuq.tsN was used. As an active layer, an InGaN layer codoped with Si and Zn was used to enhance blue emissions. When... 

Figure 26 EL spectra of InGaN/AlGaN DH blue LEDs with different forward currents.

FIGURE 6 Electroluminescence of InGaN/GaN and AlGaN/GaN double heterostructure LEDs grown by PMBE [70] and RMBE [27], respectively. 

Thus, great progress has been achieved in III-V nitride-based LEDs and LDs recently. Here, the present status of InGaN/GaN/AlGaN-based LDs is described considering the behaviour of TDs. 

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