Improved external quantum efficiency of 293 nm AlGaN UVB LED grown on an AlN template

Smart, low cost and environmentally safe AlGaN-based UVB LEDs are promising in many real world applications including medical as well as agricultural sciences. The main purpose of this work is to develop a crystal growth technique for an n-AlGaN buffer layer (BL) including an n-AlGaN current spreading layer (CSL) for obtaining a high internal quantum efficiency (IQE) from UVB-emitting multi quantum wells (MQWs). By the reduction of the edge type threading dislocation densities in the n-AlGaN CSL, as well as the optimization of the quantum well (QW) thickness, the IQE of about 42% was improved for UVB MQWs, with an emission wavelength of 294 nm. Subsequently, the external quantum efficiency improved from 2.7% to 3.3% at 20 mA under the continuous wave (CW) operation and the maximum output power also improved from 10.8 mW to 12.5 mW at 126 mA, respectively. 293 nm UVB LED light sources are very useful for the application of vitamin D3 production in the human body.

[1]  U. Zeimer,et al.  Effect of the GaN:Mg Contact Layer on the Light‐Output and Current‐Voltage Characteristic of UVB LEDs , 2018 .

[2]  Robert L. Byer,et al.  LED deep UV source for charge management of gravitational reference sensors , 2006 .

[3]  M. Holick,et al.  Ultraviolet B Light Emitting Diodes (LEDs) Are More Efficient and Effective in Producing Vitamin D3 in Human Skin Compared to Natural Sunlight , 2017, Scientific Reports.

[4]  Arne Rosén,et al.  DOAS for flue gas monitoring—I. Temperature effects in the U.V./visible absorption spectra of NO, NO2, SO2 and NH3 , 1996 .

[5]  Mim Lal Nakarmi,et al.  AlGaN-based ultraviolet light-emitting diodes grown on AlN epilayers , 2004 .

[6]  L. G. Ferreira,et al.  Influence of miscibility on the energy-gap dispersion inAlxGa1−xNalloys: First-principles calculations , 2007 .

[7]  Hideki Hirayama,et al.  Quaternary InAlGaN-based high-efficiency ultraviolet light-emitting diodes , 2005 .

[8]  Steve Young,et al.  Ultraviolet fluorescence identification of protein, DNA, and bacteria , 1995, Other Conferences.

[9]  Zlatko Sitar,et al.  High internal quantum efficiency in AlGaN multiple quantum wells grown on bulk AlN substrates , 2015 .

[10]  J. Parrish,et al.  Action spectrum for phototherapy of psoriasis. , 1981, The Journal of investigative dermatology.

[11]  Norihiko Kamata,et al.  Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes , 2014 .

[12]  Michael S. Shur,et al.  AlGaN Deep-Ultraviolet Light-Emitting Diodes with External Quantum Efficiency above 10% , 2012 .

[13]  R. Tatam,et al.  Optical gas sensing: a review , 2012 .

[14]  J. Hill,et al.  A history of photodynamic therapy. , 1991, The Australian and New Zealand journal of surgery.

[15]  Hideki Takagi,et al.  High external quantum efficiency (10%) AlGaN-based deep-ultraviolet light-emitting diodes achieved by using highly reflective photonic crystal on p-AlGaN contact layer , 2017 .

[16]  Michael Kneissl,et al.  III-Nitride Ultraviolet Emitters: Technology and Applications , 2015 .