A transmission electron microscope based technique was demonstrated which revealed all types of threading dislocations in GaN, with a high contrast over a relatively large area; even if the specimen was bent. This method used a bright-field image with the crystal oriented at the <1¯2▪¯3> zone axis, taken using multi-beam diffraction conditions. Such an image revealed all screw, edge and mixed types of threading dislocation. The multi-beam imaging technique, described here for GaN, was more generally applicable to counting the total dislocation density in a wide range of materials and structures.

Revealing all Types of Threading Dislocations in GaN with Improved Contrast in a Single Plan View Image. R.Datta, M.J.Kappers, J.S.Barnard, C.J.Humphreys: Applied Physics Letters, 2004, 85[16], 3411-3