The demand for efficient UV LEDs has been emphasized in recent years. Wavelengths below 300nm are universally germicidal, making UV disinfection one of the most promising means to fight pandemic disease outbreaks, improve water quality, and sterilize medical environments. Other applications include short-range optical communication, 3D printing, curing, medical devices, and much more. Current state-of-the-art UV LEDs are about five times less energy-efficient and 100 times more expensive per Watt than more commonly-used Hg-vapor lamps. However, solid-state LED-based UV light sources can provide many advantages such as miniaturization, rapid on/off/dim switching for smart functionality, wavelength tunability, durability, and low power consumption. In order to realize these advantages and replicate the disruption achieved by white and blue LEDs, novel technologies for efficient UV LEDs are needed.
Researchers at the University of California, Santa Barbara have introduced a design for ultraviolet (UV) or far-UV LEDs that incorporates a novel doped multilayer structure that dramatically improves the performance of these devices. The novel multilayer structure combines regions of higher Al composition (compared to adjacent layers) with an undulating emitting region and controlled buffer layer crystal quality to promote radiative recombination and enhance efficiency. Compared to nitride UV LEDs without the novel multilayer structure, this technology demonstrates an approximate 300% improvement in output power and the surface morphology of the active region is extremely smooth by comparison. This plays an important role in upgrading light emission efficiency due to electron and hole localization from the disc-hillocks, and extremely smooth surfaces on top of the disc-hillocks enable sharp quantum well heterostructures which increase carrier localization further.
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Multilayer structure, UV LEDs, Far-UV LEDs, Doped layers, Al composition, Radiative recombination, Efficiency improvement, Output power, Surface morphology, Quantum well heterostructures, Electron and hole localization, Enhanced performance, Improved reliability, Longer lifetime, Uniformity across growth wafers