Abstract—A theoretical existence of misfit dislocation (MD) and strain relaxation has been reported in compositionally step graded InxGa1-xN grown on the two favored planes of GaN using the total dislocation energy at each interface. The results also compared with uniform layer of In0.17Ga0.83N and In0.14Ga0.86N grown differently on GaN. Due to having residual strain and a step increase in indium (In) composition a lower misfit strain in upper layers and hence larger critical thickness at each interface has been reported. These effects significantly reduced the misfit dislocation from 2.6×105 cm-1 to 9.5×104 cm-1 and from 4.0×105 cm-1 to 1.5×105 cm-1 in step-graded In0.14Ga0.86N(500nm)/In0.09Ga0.91N(100nm)/In0.05Ga0.95N(100nm)/GaN layers grown on (1122) and (1101) planes respectively instead of an without graded In0.14Ga0.86N (700nm)/GaN layer. A small residual strain of 0.0007 after 700 nm graded layer thickness has been reported with 87.04% strain relaxation.

Index Terms—Critical thickness, burger vector, misfit dislocation, threading dislocation, step-graded layer.

M. A. Hossain is with Department of Electrical and Electronic Engineering of Khulna University of Engineering and Technology (KUET), Khulna-9203, Bangladesh (e-mail: arafat_kuet_eee@ yahoo.com).
M. M. Hasan is with the Department of Advanced Technology Fusion, Saga University, Japan, and on leave from the Khulna University of Engineering and Technology (KUET), Khulna-9203, Bangladesh (e-mail: hasanimahbub@yahoo.com).
M. R. Islam is with Department of Electrical and Electronic Engineering of Khulna University of Engineering and Technology (KUET), Khulna-9203, Bangladesh (e-mail: rafiq043@yahoo.com).

Cite: Md. Arafat Hossain, Md. Mahbub Hasan, and Md. Rafiqul Islam, "Strain Relaxation via Misfit Dislocation in Step-Graded InGaN Heteroepitaxial Layers Grown on Semipolar (1122) and (1101) GaN," International Journal of Applied Physics and Mathematics  vol. 2, no. 1, pp. 049-053, 2012.