Empty core screw dislocations formed on 6H-SiC(0001) during hydrogen etching

Hydrogen etching was carried out on the (0001)-oriented 6H-SiC wafer at various temperatures in the range from 1450 to 1650 °C. Surface topography and morphology was characterized by the atomic force microscope (AFM). Optimal conditions have been found, under which all scratches due to the polishing process are efficiently removed and the atomically smooth, clean surface of SiC(0001) is achieved. The most characteristic elements observed on the perfectly etched surface were straight-line steps of equal height and nearly the same width. The AFM imaging revealed also intrinsic defects of the samples. Conditions have been found for maintaining the saturation of etching products on the surface at the level enabling the empty core dislocations to be formed during etching. The observed population of the dislocations ranges between 107 and 108 cm− 2. Burgers vectors of the dislocations as evaluated on the basis of Frank's model are equal to 2 or 3 lattice constants.