On the origin of dislocation generation and annihilation in α -Ga2O3 epilayers on sapphire
Date
2019-10
Authors
Ma, Tongchuan
Chen, Xuanhu
Kuang, Y.
Li, Li (Lily)
Kremer, Felipe
Tan, Hark Hoe
Jagadish, Chennupati
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American Institute of Physics (AIP)
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.
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Applied Physics Letters
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Journal article
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