Misfit Dislocation Reduction of In_xGa_(1-x)N/GaN Heteroepitaxy Using Graded Layer

摘要

The performances of heterostructural devices are often limited by misfit dislocation. In this paper, a theoretical approach for misfit dislocation reduction of wurtzite In_xGa_(1-x)N/GaN is presented. The linear and exponential grading techniques have been modeled for the reduction of dislocation. An energy balance model has been taken into consideration and modified for wurtzite structure to evaluate the misfit dislocation density. The value of misfit dislocation has been reduced from 7.112×10~(10) cm~(-2) to 6.19×10~6 cm~(-2) and 7.039×10~(10) cm~(-2) to 6.121×10~6 cm~(-2) at the plane 1/3<1123 > {1122 } and 1/3<1123 >{1101} respectively for linear grading. In case of exponential grading the dislocation density has been reduced to 2.762×105 cm-2 for both slip systems. Because of tapered grading coefficient a tapered dislocation profile has been reported in case of exponential grading technique. Finally, a comparative study has been shown among without graded, linear and exponential grading.