Dislocation-Free and Atomically Flat GaN Hexagonal Microprisms for Device Applications

Maryam Khalilian, Zhaoxia Bi, Jonas Johansson, Filip Lenrick, Olof Hultin, Jovana Colvin, Rainer Timm, Reine Wallenberg, Jonas Ohlsson, Mats Erik Pistol, Anders Gustafsson, Lars Samuelson

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskriftPeer review


III-nitrides are considered the material of choice for light-emitting diodes (LEDs) and lasers in the visible to ultraviolet spectral range. The development is hampered by lattice and thermal mismatch between the nitride layers and the growth substrate leading to high dislocation densities. In order to overcome the issue, efforts have gone into selected area growth of nanowires (NWs), using their small footprint in the substrate to grow virtually dislocation-free material. Their geometry is defined by six tall side-facets and a pointed tip which limits the design of optoelectronic devices. Growth of dislocation-free and atomically smooth 3D hexagonal GaN micro-prisms with a flat, micrometer-sized top-surface is presented. These self-forming structures are suitable for optical devices such as low-loss optical cavities for high-efficiency LEDs. The structures are made by annealing GaN NWs with a thick radial shell, reforming them into hexagonal flat-top prisms with six equivalents either m- or s-facets depending on the initial heights of the top pyramid and m-facets of the NWs. This shape is kinetically controlled and the reformation can be explained with a phenomenological model based on Wulff construction that have been developed. It is expected that the results will inspire further research into micron-sized III-nitride-based devices.

Tidigt onlinedatum2020 juni 24
StatusPublished - 2020 juli 28

Ämnesklassifikation (UKÄ)

  • Den kondenserade materiens fysik
  • Nanoteknik


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