A theoretical approach for the dislocation reduction of wurtzite InxGa1−xN/GaN heteroepitaxy

This paper reports the numerical estimation of misfit dislocation in wurtzite In_xGa_1-xN/GaN heterostructure. The misfit strain increases with the increase of lattice mismatch for higher In content. The exponential grading technique has been modelled for the reduction of dislocation. An energy balance model has been modified to evaluate the misfit dislocation density. The dislocation density has been reduced from 68.07*10^9 cm^-2 to 0.288*10^6 cm^-2 which is tapered in nature and help to promote annihilation and coalescence reactions between threading dislocations without unwanted tangling and pinning events. Finally, a comparative analysis has also been shown between without graded layer having constant composition and exponentially graded layer In_0.2Ga_0.8N/GaN.