Aluminum-gallium-nitride (AlGaN) -based deep ultraviolet LEDs have attracted the attention of researchers due to their potential applications in sterilization, water purification, phototherapy, and high-speed optical communications that do not rely on sunlight.
The aluminum-gallium-nitride-based deep ultraviolet LED can efficiently convert electric energy into light energy because one of the bottom layers grows in a stepwise manner. Scientists are exploring ways to increase their efficiency in converting electrical energy into light energy.
Kazunobu Kojima and colleagues at Tohoku University in Japan use a variety of specialized microscopy techniques to understand how aluminum-gallium-nitride-based LED structures affect efficiency.
Source: Tohoku University
The news revealed that the researchers had grown a layer of aluminum nitride on a very small angled sapphire substrate. Next, an aluminum gallium nitride coating containing silicon impurities is grown on the aluminum nitride layer. Three aluminum gallium nitrogen quantum wells are grown on it. Quantum wells are very thin, limiting subatomic particles (electrons and holes) to dimensions that are perpendicular to the surface of the layer, but not limiting the movement of these particles in other dimensions. Finally, the top of the quantum well is covered by an electron blocking layer formed by aluminum nitride and aluminum gallium nitrogen containing magnesium impurities. Researchers have thus produced aluminum gallium nitrogen-based LEDs.
This microscopic study revealed that a stepped structure was formed between the GaN layer and the AlGaN layer at the bottom. These stepped structures affect the shape of the quantum well layer above them, and the stepped structures at the bottom are connected with the tiny distortions they cause in the quantum well layer to form gallium-rich stripe structures, and these stripe structures become the current in the aluminum gallium nitrogen coating. Microchannel.
Researchers said that the intense movement of electrons and holes in microchannels and quantum well layers appears to improve the efficiency of LEDs in converting electrical energy to light energy. Based on this finding, the research team plans to produce more efficient aluminum gallium nitrogen based deep ultraviolet LEDs.