Today, the first generation semiconductor materials, represented by Si and Ge, and the second generation semiconductor materials, such as GaAs and InP, are gradually unable to meet the needs of people because of their own defects. Si has a narrow band gap and an indirect band gap and a small breakdown voltage, which restricts its application in the field of Optoelectronics and high frequency and high-power devices. Although GaAs has excellent optoelectronics and microelectronics properties, its band gap is narrow and the heat conduction efficiency is low, which limits its application in visible light and ultraviolet photoelectronic devices. Use. Compared with the traditional semiconductor materials such as Si and GaAs, the third generation semiconductor materials, such as III nitride and SiC, have the characteristics of wide band gap, high breakdown electric field, high electron mobility and radiation resistance. It is suitable for the manufacture of integrated optoelectronic devices with radiation resistance, high frequency, high power and high density.

The ultraviolet spectrum range from 100 to 400nm is generally subdivided into three segments: UV-A long wave ultraviolet band (315 to 400nm), UV-B in ultraviolet band (280 to 315nm), UV-C short wave ultraviolet band (200 to 280nm) and ultra deep ultraviolet band (100 to 200nm). Since the ultraviolet light has a shorter wavelength compared to the visible light, when the wavelength is reduced to 365nm, the direct band gap semiconductor material with a band gap greater than 3.4eV is needed as the base material of the device. In the current wide band gap semiconductor materials, AlGaN is an ideal material for realizing the light source of this band, and its luminous wavelength can cover the ultraviolet light of the 210-365nm (as shown in the picture). Therefore, AlGaN based UV LED is the most ideal UV light source.

Some overseas research teams began to study the near ultraviolet LED very early. In 1997, the near ultraviolet LED with luminous wavelength of 385nm and 412nm was produced by P.M.Mensz of Philips, and its output power was 1.5mW. The next year, MukaiT et al. And others adopted the InGaN/AlGaN structure in the quantum well area of LED. The UV LED with the output power of 5mW was successfully developed, its luminous wavelength was 371nm, and the external quantum efficiency (EQE) reached 7.5%. In 2001, the Japanese Optoelectronics Laboratory used MOPVE lateral epitaxial growth technology (LEO) to develop a near ultraviolet LED with a luminous wavelength of 382nm and an output power of 15.6mW under 20mA injection current. The external quantum efficiency reached 24%. In 2002, the 400nm near ultraviolet LED of Motokazu Yamada et al. In Japan and the output power of the optical output were 20. The mA injection current is 22mW, and the external quantum efficiency is 35.5%. In 2005, the 410nm near UV LED grown on the graphic sapphire substrate by D.S.Wuu et al. Under the 20mA injection current, the optical power and the external quantum efficiency were 10.4mW and 14.1% respectively. In 2008, the 405nm of the H Sakuta and others reported by the long state company of Japan was near ultraviolet LED, 20m. The external quantum efficiency under A is 46.7%.

At present, the application of UV LED has been involved in various fields. In addition to the common use of ultraviolet LED to stimulate RGB phosphors in the field of lighting, the deep ultraviolet light band below 300nm can also be used in UV identification, sterilization, liquid detection and analysis. The ultraviolet light of 300-400nm can be applied to medical light. Treatment, polymer and ink printing technology, identification and other fields.

Ultraviolet LED has obvious advantages in performance, ordinary ultraviolet light sources need external lenses to make the light to achieve sufficient brightness and uniformity. Ultraviolet LED has high brightness, high concentration and so on. Its energy consumption is low and its service life is long.