Quality-Improved GaN Epitaxial Layers Grown on Striped Patterned Sapphire Substrates Ablated by Femtosecond Laser

Abstract

In this work, we propose a new approach to create striped patterned sapphire substrate (PSS) under the circumstance that grooved patterned sapphire substrate technology exhibits more potential to reduce dislocation density in GaN (gallium nitride) epilayers. The striped grooves of patterned sapphire substrate are ablated by femtosecond laser. After the process of metal-organic chemical vapor deposition (MOCVD) method, the c-plane GaN epitaxial layers grown on striped PSS have larger crystallite size, which brings much less crystal boundary. There is much less compressive stress between the GaN crystals which improves the smoothness and compactness of GaN epilayers. This result demonstrates a significant improvement in the crystallinity of the c-plane GaN epitaxial layers grown on striped PSS.

Cerium-Oxide-Nanoparticle-Decorated Zinc Oxide with Enhanced Photocatalytic Degradation of Methyl Orange

“…Here, a and c are the lattice constants of the crystal. The sizes of ZnO and CeO 2 crystals can be calculated by Scherer's equation [40]:…”

ZnO Nanostructures Doped with Various Chloride Ion Concentrations for Efficient Photocatalytic Degradation of Methylene Blue in Alkaline and Acidic Media

“…In addition, the doping of Cl − into ZnO can further alter the distance in crystal structure as well as in diffraction angle. Moreover, the crystallite size of the as-prepared samples was evaluated by Scherer's relation [50].…”

Simultaneous doping of sulfur and chloride ions into ZnO nanorods for improved photocatalytic properties towards degradation of methylene blue

“…In addition the doping of S-Cl into ZnO can further alter the distance in crystal structure as well as in diffraction angle. Moreover, the crystallite size of the as-prepared samples was evaluated from Scherer's relation [40].…”