Strain relaxation and strong impurity incorporation in epitaxial laterally overgrown GaN: Direct imaging of different growth domains by cathodoluminescence microscopy and micro-Raman spectroscopy

• DOI: 10.1063/1.123071
• Publication Date: 2002-07-26T13:31:28Z
• Authors: F. Bertram; T. Riemann; J. Christen; A. Kaschner; A. Hoffmann; C. Thomsen; K. Hiramatsu; T. Shibata; N. Sawaki
• Keywords: Cathodoluminescence; Coalescence (physics); Stress relaxation

Epitaxial lateral overgrowth GaN structures oriented along the 〈112_0〉 direction were comprehensively characterized by cathodoluminescence (CL) microscopy and micro-Raman spectroscopy. CL directly visualizes significant differences between overgrown areas on top of SiO2 mask coherently grown regions stripes in quantitative correlation with spectroscopy mapping local strain free carrier concentration. The shows a partial relaxation high concentration that strongly broadens luminescence. A strong impurity incorporation is evidenced coalescence regions. In contrast, luminescence from coherent (0001) growth dominated narrow excitonic emission, demonstrating superior crystalline quality.