Chapter 6
AlGaN-Based Multiple-Quantum-Well
Materials and UV LEDs
As illustrated in Fig. 6.1, ultraviolet (UV) light, which is shorter than the wavelength
of visible light, is attractive in various application scenarios. Among them, UV-C
light (250–280 nm) can destroy nucleic acids, the genetic material of microorganisms, through photochemical action. UV treatment can prevent the replication of
microorganisms and cause the death of microorganisms, hereby sterilizing water,
air and the surfaces of object. The band gap of AlGaN is 3.43–6.04 eV. The corresponding band edge radiation wavelength is 365–210 nm, which makes AlGaNbased UV LEDs attractive for a broad range of applications in water/air purification,
sterilization, bio-probe, medical, and non-field-of-sight communication. UV LEDs
have attracted extensive international research interest [1]. In the field of disinfection, AlGaN-based UV LEDs have the following advantages: First, small size has
great potential in portable, highly integrated products. Second, AlGaN-based UV
LEDs are rugged and durable, more resistant than the mercury lamp with the quartz
glass. Third, AlGaN-based UV LEDs have higher energy efficiency. Compared with
mercury lamps, the energy consumption of UV LEDs can be as low as 70%. Fourth,
UV LEDs are eco-friendly. UV LEDs do not contain harmful substances such as
mercury, which are certified by RoHS (Restriction of Hazardous Substances). Fifth,
UV LEDs have lower working voltage, only about 3.3–4.5 V. Compared with the
high-voltage mercury lamp, the safety is much improved and the cost of the driving
circuit is reduced. Sixth, the power of UV LEDs is easier to adjust. Seventh, the
cooling system for UV LEDs is much simpler, further reducing system cost. Eighth,
the optical system is simple and more suitable for practical applications. UV LEDs
have a compact beam angle and a uniform beam pattern without an external lens,
thereby reducing the cost and enhancing the system reliability. Because of these
advantages, AlGaN-based UV LED technology is becoming an attractive option for
the UV sterilization industry.
However, achieving high efficiency AlGaN-based UV LEDs are still facing many
technical difficulties and obstacles such as low internal quantum efficiency, low
current injection efficiency, and low light extraction efficiency. This chapter will
© Science Press and Springer Nature Singapore Pte Ltd. 2020
J. Li et al., III-Nitrides Light Emitting Diodes: Technology and Applications,
Springer Series in Materials Science 306,
https://doi.org/10.1007/978-981-15-7949-3_6
93
AlGaN-Based Multiple-Quantum-Well
Materials and UV LEDs
As illustrated in Fig. 6.1, ultraviolet (UV) light, which is shorter than the wavelength
of visible light, is attractive in various application scenarios. Among them, UV-C
light (250–280 nm) can destroy nucleic acids, the genetic material of microorganisms, through photochemical action. UV treatment can prevent the replication of
microorganisms and cause the death of microorganisms, hereby sterilizing water,
air and the surfaces of object. The band gap of AlGaN is 3.43–6.04 eV. The corresponding band edge radiation wavelength is 365–210 nm, which makes AlGaNbased UV LEDs attractive for a broad range of applications in water/air purification,
sterilization, bio-probe, medical, and non-field-of-sight communication. UV LEDs
have attracted extensive international research interest [1]. In the field of disinfection, AlGaN-based UV LEDs have the following advantages: First, small size has
great potential in portable, highly integrated products. Second, AlGaN-based UV
LEDs are rugged and durable, more resistant than the mercury lamp with the quartz
glass. Third, AlGaN-based UV LEDs have higher energy efficiency. Compared with
mercury lamps, the energy consumption of UV LEDs can be as low as 70%. Fourth,
UV LEDs are eco-friendly. UV LEDs do not contain harmful substances such as
mercury, which are certified by RoHS (Restriction of Hazardous Substances). Fifth,
UV LEDs have lower working voltage, only about 3.3–4.5 V. Compared with the
high-voltage mercury lamp, the safety is much improved and the cost of the driving
circuit is reduced. Sixth, the power of UV LEDs is easier to adjust. Seventh, the
cooling system for UV LEDs is much simpler, further reducing system cost. Eighth,
the optical system is simple and more suitable for practical applications. UV LEDs
have a compact beam angle and a uniform beam pattern without an external lens,
thereby reducing the cost and enhancing the system reliability. Because of these
advantages, AlGaN-based UV LED technology is becoming an attractive option for
the UV sterilization industry.
However, achieving high efficiency AlGaN-based UV LEDs are still facing many
technical difficulties and obstacles such as low internal quantum efficiency, low
current injection efficiency, and low light extraction efficiency. This chapter will
© Science Press and Springer Nature Singapore Pte Ltd. 2020
J. Li et al., III-Nitrides Light Emitting Diodes: Technology and Applications,
Springer Series in Materials Science 306,
https://doi.org/10.1007/978-981-15-7949-3_6
93