Near-IR Emission of InGaN Quasi-quantum Dots on Non-polar GaN Nanowire Structures

In group III-nitride based semiconductor structures, the incorporation of high-indium-composition InGaN has been severely limited by extremely inefficient strain-induced polarization fields and prohibitively large defect densities. So far, there is no clear approach to solve this issue. Here, we have shown a new approach to incorporate high concentrations of indium in the InGaN structure by using a non-polar quasi-quantum dot heterostructure. This unique epitaxial growth was achieved by integrating a 1-dimensional nanowire and a 0-dimensional quantum dot structure using an MOCVD system. The formation of a high-efficiency quantum-sliding heterostructure and high-quality nanowire structure was confirmed by FE-SEM and TEM measurements. Furthermore, it has been suggested that such a quantum-dot structure can dramatically improve radiative recombination through a new sliding bandgap mechanism. We also found that non-polar quantum dots can not only incorporate more indium than conventional multi-quantum well structures grown on the nanowire structure, but also significantly improve crystalline quality. The PL results verified that the wavelength of quantum dots fabricated on the nanowire structure can easily shift up to 913 nm. The first demonstration in the integration of nanowire and quantum dot structures will open a new avenue to break through the limitations of high indium incorporation in photonic semiconductor systems.