physica status solidi (a) · 2011 · 110 citations · 8 references
EngineeringElectrical EngineeringMaterials ScienceElectronic MaterialsOptoelectronicsSemiconductor DevicesLight SourcesLight-emitting DiodesLuminescent MaterialsSemiconductor Device MaterialsSolar CellsWide-bandgap Semiconductor DevicesExternal Quantum EfficiencyFlip-chip Light-emitting DiodesGallium Nitride (Gan) MaterialsLight ExtractionLight-emitting DevicesLight-emitting Diode MaterialsUltraviolet Light-emitting DiodesUv Light Applications
Abstract We report on the fabrication and characterization of high efficiency ultraviolet (UV) light emitting diodes (LEDs) with emission wavelength ranging from 255 to 355 nm. Epi‐layers of UV LEDs were grown on AlGaN templates with sapphire substrates. Flip‐chip configuration without removing sapphire is used for characterization of the UV LEDs. External quantum efficiencies (EQEs) over 3% were obtained for all the investigated wavelengths with maximum value reaching 5.1% for 280 nm LED. Under RT DC operation at a current of 500 mA, output powers of 38, 77, and 64 mW were measured for 257, 280, and 354 nm, respectively. By using enhanced light extraction technologies, such as, moth‐eye structure on the back side of the sapphire substrate, we expect to improve these values by up to 50%.
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M. Asif Khan, M. Shatalov, H. P. Maruska et al. · Japanese Journal of Applied Physics · 2005 · 420 citations · Full text
Hideki Hirayama, Yusuke Tsukada, Tetsutoshi Maeda et al. · Applied Physics Express · 2010 · 297 citations