Nondestructive visualization of threading dislocations in GaN by micro raman mapping

Threading dislocations (TDs) in a HVPE-grown c-plane (0001) GaN single crystal were analyzed by micro Raman spectroscopy mapping. The mapping image exhibited the pairs of higher and lower wavenumber regions of E-2(H) peak shift of GaN, which corresponded to the compressive and tensile strains due to TDs. By comparing X-ray topography and etch pit images, the contrasts are considered as the edge component of TDs. By analyzing the existing 290 TDs in 80 x 80 mu m(2), the directions of the contrast were mainly dominant toward < 10 (1) over bar0 >. A few brighter contrasts toward < 11 (2) over bar0 > were also observed. These TDs are affiliated with Burgers vectors b = a/3 < 11 (2) over bar0 >, and b = a < 01 (1) over bar0 >, respectively. Judging from experimental and simulated result, it is confirmed that the contrast in the Raman mapping image of the b - a < 0 (1) over bar 10 > has a larger magnitude than the b = a/3 < 11 (2) over bar0 >. (C) 2019 The Japan Society of Applied Physics