摘要： •Structural and surface morphological properties of AlGaN with different Al composition were investigated.•Increasing the Al composition growth rate decreases with dislocation increases, which are confirmed by wet etch and HRXRD.•Surface morphology are investigated in H3PO4 etchant and α, β and γ type pits are observed.•PL intensity enhanced due to the increases surface roughness of the AlGaN film after etching. In this work, AlxGa1−xN epilayers have been grown on sapphire substrate with GaN template by the metal organic chemical vapor deposition (MOCVD) method. The structural and morphological properties of these samples have been investigated and compared. The growth rate of AlGaN has been found to decrease with increasing Al composition. By increasing Al composition of AlGaN epilayer, tilt and twist angle has been found to increase, indicating higher threading dislocation density. Surface morphology and dislocation density (DD) have been investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Different types of dislocation etch pits have been observed in AlxGa1−xN/GaN epilayers, using orthophosphoric acid (85% H3PO4) as defect selective etchant. Three types of etch pits like screw type (α), edge type (β) and mixed type (α+β) dislocations have been observed. The mechanism of etch pits formation has been explained using Cabrera’s thermodynamic model. The etch pit density (EPDs) has been correlated with threading dislocation density (TDs) estimated using HRXRD measurements. Photoluminescence (PL) studies have revealed an increase in intensity of near band edge emission due to etching. 出版者： Kidlington: Elsevier B.V 出版日期： 2014-12-15 出處： Journal of alloys and compounds, 2014-12, Vol.616, p.363-371 版權： 2014 Elsevier B.V. 版權： 2015 INIST-CNRS 識別號： ISSN: 0925-8388 識別號： EISSN: 1873-4669 識別號： DOI: 10.1016/j.jallcom.2014.07.170
