Elimination of threading dislocations in alpha-Ga2O3 by double-layered epitaxial lateral overgrowth

We demonstrated double-layered epitaxial lateral overgrowth of alpha-Ga(2)O(3)by halide vapor phase epitaxy. The second ELO alpha-Ga(2)O(3)were regrown epitaxially and selectively through the windows of the patterned masks which were prepared on an ELO alpha-Ga2O3. The ELO islands coalesced step-by-step due to the nested-structure mask pattern. No threading dislocation was found by TEM not only above the masks but also above the windows of the second ELO pattern. The dislocation density was estimated to be less than 5 x 10(6) cm(-2). We obtained a continuous crystalline alpha-Ga2O3 with a low density of dislocations in the entire second-ELO surface.