This chapter is designed to discuss III-nitride ultraviolet light emitting sources. Research on III-nitrides started 80 years ago when the first aluminum nitride (AlN) was synthesized from metallic aluminum. After that, gallium nitride (GaN) and its family have been grown with various methods and after several breakthroughs, finally blue/violet light emitting diodes (LEDs) were demonstrated. Following the commercialization of blue laser diodes, the interest shifted towards shorter wavelength light emitters ultra violet (UV LEDs) and laser diodes. UV light emitters resemble well-known blue/violet LEDs, such as double heterostructure or quantum well (QW) active layer structure. A blue/ violet LED structure can be modified for UV emission by simply decreasing the indium content in the InGaN active layer. The minimum wavelength that can be achieved using ternary InGaN active layers is ∼ 365 nm. A number of groups have demonstrated UV LEDs and the quest for high-power devices still continues. Because of high density of dislocations and doping difficulties, realization of high efficiency UV light emitters is more challenging than that of blue/violet light emitters. This chapter reviews the growth, processing, and characterization of ultraviolet light emitters based on the III-nitride material system, with more emphasis on deep UV LEDs, because of the challenges involved.
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