INGAN/GAN based semipolar green converters

Abstract

In order to achieve highly efficient green light emission, we are investigating the realization of InGaN-based luminescence conversion structures optically pumped by a blue LED. Using selective area metalorganic vapor phase epitaxy, we have grown inverted pyramid structures. On the side facets of these structures, semipolar InGaN/GaN multi-quantum wells can be deposited which may have promising characteristics for high luminescence conversion efficiencies. In order to enhance the green emission intensity, both the absorption of the blue excitation light and the conversion to green light must be optimized. By varying the growth parameters, we could stabilize the formation of {101¯1} semipolar facets resulting in better quantum well morphology and hence better green light conversion. Moreover, the QW number is optimized to make a balance between thermal load – decreasing the quality of the early grown quantum wells – and the lower quality of the quantum wells grown on top of many others. The thermal load has been identified as a very critical parameter for such structures emitting green light at about 505nm.