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

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 (1 (1) over bar 00) direction and the microfacet structure is composed of the (0001) and {11 (2) over bar2} planes. With a large occupancy of the mask opening within a period, both facets simultaneously appear and emit different colors. For example, the {11 (2) over bar2} facet QWs emit blue and the (0001) facet QWs emit green. On the other hand, with a small occupancy of the mask opening, the {11 (2) over bar2} 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. (c) 2007 American Institute of Physics.