Additive color mixture of emission from InGaN∕GaN quantum wells on structure-controlled GaN microfacets

Abstract

Altering the mask geometry controls the apparent emission color from InGaN∕GaN quantum wells (QWs) grown on GaN microfacets formed by regrowth on SiO2 mask stripes over a wide spectral range, including white. The mask stripes are along the ⟨11¯00⟩ direction and the microfacet structure is composed of the (0001) and {112¯2} planes. With a large occupancy of the mask opening within a period, both facets simultaneously appear and emit different colors. For example, the {112¯2} facet QWs emit blue and the (0001) facet QWs emit green. On the other hand, with a small occupancy of the mask opening, the {112¯2} facets become dominant and a greenish-blue light is emitted. To synthesize these spectra, the mask patterns are designed so that two different microfacet structures are included within a period. Hence, the macroscopically observed emission color, which depends on the pattern design, can change from green to purple through white due to the additive color mixture.