https://doi.org/10.15407/jopt.2018.53.181
Optoelectron. Semicond. Tech. 53, 181-187 (2018)
V.P. Veleschuk, A.I. Vlasenko, Z.K. Vlasenko, D.N. Khmil’, O.M. Kamuz, S.G. Nedilko, V.P. Scherbatsky, D.V. Gnatyuk, V.V. Borshch, M.P. Kisselyuk
THE MECHANISMS OF THE APPEARANCE OF VISIBLE PARASITIC LUMINESCENCE IN THE ULTRAVIOLET LED’s 365 nm
The mechanism of appearance of visible parasitic luminescence in the light emitting diodes (LEDs) of ultraviolet (UV) radiation 365 nm has been studied. UV LEDs with a maximum of 365 nm has a wide range of applications, for example: polymerization, fluorescence microscopy in medicine and biology, luminescent analysis. However, the InGaN/AlGaN/GaN heterostructures have a few problems, including the so-called "yellow" luminescence. Therefore, in addition to work on the quantum efficiency increase, studies are carried out to reduce the visible parasitic luminescence in the UV LEDs. To find ways to reduce the intensity of visible luminescence, it is necessary to know the mechanism of its occurrence. The industrial InGaN/AlGaN/GaN UV LEDs with a maximum of 365…370 nm have been investigated. It has been ascertained that visible parasitic luminescence in these LEDs consists of two spectral parts - the so-called yellow luminescence and blue luminescence, which are caused by defects and complexes of defects with doping impurities. Luminescence in the yellow-green part of the spectrum (maximum at 555 nm) is dominant at the temperature 300 K, and luminescence in the blue spectral part (400…470 nm) at 77 K. It has been shown that the dominant mechanism for appearance of visible luminescence in the UV LEDs (365 nm) is electroluminescence, because with increasing the voltage at the p-n junction the yellow band of electroluminescence appears first; photoluminescence in the UV LEDs at T = 77 K at the excitation of UV radiation from a similar LED is practically absent. At the same time, when the current increases at T = 77 K, the yellow band of electroluminescence appears, and intensity grows. Acknowledgements – This work was supported by the National Research Fund of Ukraine. Keywords: UV LED 365 nm, luminescence.