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Metal organic vapor phase deposition on etched 4-inch-diameter sapphire wafers is used to create low-defect-density gallium nitride templates.
Visible emitting LEDs based on gallium nitride (GaN) materials have made tremendous progress since their initial development in the early 1990s. Indeed, these LEDs are now in everyday use in many applications, e.g., for solid state lighting, and for backlighting in televisions and smartphones. LED technology, however, also has several inherent problems. These include decreasing efficiency under high injection current (droop), color change with increasing current, and poor efficiency in the green and yellow parts of the spectrum. These problems are associated with the natural polar (0001) crystal plane of wurtzite GaN, on which commercial LEDs are based, with the use of ‘c-plane’ sapphire substrates.