On the origin of dislocation generation and annihilation in α-Ga2O3 epilayers on sapphire
Abstract
Epitaxial film quality is critical to the success of high-performance α-Ga2O3 vertical power devices. In this work, the origins of threading dislocation generation and annihilation in thick α-Ga2O3 films heteroepitaxially grown on sapphire by the mist-CVD technique have been examined by means of high-resolution X-ray diffraction and transmission electron microscopies. By increasing the nominal thickness, screw dislocations exhibit an independent characteristic with a low density of about 1.8 × 106 cm-2, while edge dislocations propagating along the c-axis are dominant, which decrease down to 2.1 × 109 cm-2 in density for an 8 μm-thick α-Ga2O3 layer and exhibit an inverse dependence on the thickness. In the framework of the glide analytical model, parallel edge dislocations are generated at the interface due to the misfit-induced strain relaxation, while the dislocation glide and coalescence result in the annihilation and fusion behaviors. The optimal thick α-Ga2O3 with low dislocation densities may provide a prospective alternative to fully realize α-Ga2O3 power devices.
- Publication:
-
Applied Physics Letters
- Pub Date:
- October 2019
- DOI:
- 10.1063/1.5120554
- Bibcode:
- 2019ApPhL.115r2101M