Full text loading...
Schematic of the three step-graded buffer structures studied in this work. The buffers span about the same range of lattice misfit. Buffer C is essentially the same as butter B but contains two dilute nitride intermediate layers.
TEM dark-field image and RSM of the step-graded buffer A. Dislocations form in the first three grading layers (and in the substrate below) but are absent in the subsequent layers with N concentrations . Tensile strain in this part of the buffer has eventually led to film cracking.
TEM bright-field image and the RSM of the step-graded buffer B. Almost complete strain relaxation is achieved by efficient dislocation formation across the whole grading part of the buffer. Microtwins penetrating the surface have led to the formation of roof-shaped surface undulations.
TEM bright-field image and RSM of the step-graded buffer C containing two intermediate layers. Already the lower layer has acted as an efficient dislocation blocker suppressing the formation of dislocations and strain relaxation in the upper part of the buffer. Similar as for buffer A, the accumulation of tensile strain has eventually led to film cracking.
Article metrics loading...