Polychromatic light emission from single InGaN quantum wells grown on pyramidal GaN facets

We have studied the properties of InGaNGaN quantum wells grown on epitaxially laterally overgrown GaN stripes. The stripes have a triangular cross section due to {11 2- 2} crystalline facets. We have observed that the integrated light emission from such structures is uniformly polychromatic over a wide range of the visible spectrum. Using cathodoluminescence techniques, we find that the local emission wavelength increases steadily along the facets, in the direction away from the substrate. The gradient in the emission wavelength is related to the dependence of the quantum well width on the relative position along the facet. The continuous variation of the quantum well properties causes a uniform, polychromatic luminescence band. For some conditions, such distribution can resemble solar-white light emission. This approach can be used to produce an integrated white light source for monolithically integrated white light-emitting diodes.