Study On Optoelectronic Characteristics And Sterilization Application Of Deep-Ultraviolet Light-Emitting Diode

As a new generation of deep-ultraviolet light source,deep-ultraviolet lightemitting diode(LED)has many advantages,such as small and compact,various emission wavelengths,no pollution and so on.At present,deep-ultraviolet LED has been used in disinfection,but it still has the problem of low quantum efficiency.In this paper,the research background,the harm and application of ultraviolet,the development and application of deep-ultraviolet LED are introduced.Then the research work on the photoelectric characteristics and sterilization application of deepultraviolet LED is described.In the part of photoelectric characteristics,the 450-nm parasitic emission peak of 275-nm ultraviolet LED is studied in detail.Through careful comparison and analysis of electroluminescence and photoluminescence spectra at different injection levels and different temperatures,the mechanism of exciton assisted radiation recombination is found,that is,exciton generated in the middle of the band gap enhances radiation recombination through other impurity-trap levels.For the studied deep-ultraviolet LED samples,the radiative impurity-trap level system in the band gap can not be ignored.It includes two kinds of impurities with different energy levels,3.80 eV and 2.75 eV,respectively.The former establishes a sub-band edge,which is similar to the energy exit of the system,and contains a series of hydrogen-like excitons with temperature lower than 100 K,which is similar to the energy entrance of the system.On the one hand,these excitons absorb carriers from the band edge and reduce the band-edge recombination.On the other hand,they transfer energy to lower impurity levels,enhance radiative recombination and produce 450-nm parasitic emission peak.In the application of sterilization and disinfection,several kinds of deep-ultraviolet LED with different wavelengths is studied,including optical characteristics,electrical characteristics,design of multi-chip light source and uniformity of irradiation.The difference between the spectra of different deep-ultraviolet LEDs is analyzed,which is mainly due to the diferent emission wavelengths,and the spectral change is not obvious in the temperature range of 25～50℃.The multi-chip light sources with different wavelengths of deep-ultraviolet LED are designed and fabricated by using optical model simulation.The uniformity test shows that the illumination uniformity of these kinds of deep-ultraviolet LED multi-chip light sources can reach about 80%in the circular area with a diameter of 9 cm,which is 2 cm or 2.5 cm away from the light source substrate.When the drive current is 10 mA the average ultraviolet irradiation intensity can reach more than 200 μW/cm2.These kinds of light sources can achieve high irradiance and uniformity at the same time.