A Transmission Electron Microscopy Observation of Dislocations in GaN Grown on (0001) Sapphire by Metal Organic Chemical Vapor Deposition

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概要

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• A transmission electron microscopy (TEM) observation of dislocations in GaN grown on (0001) sapphire by metal organic chemical vapor deposition (MOCVD) was carried out in this study. The GaN film was rotated 30° around the $c$-axis in the growth plane against the substrate. The finding of this research, according to TEM analysis, is that about 3% (or less) of the threading dislocations are pure screw ($\mathbf{b} = \langle 0001 \rangle$) and 20% are pure edge ($\mathbf{b} = 1/3 \langle 11\bar{2}0 \rangle$). The remaining threading dislocations, about 77%, are mixed-type dislocations; that is the major dislocation type in the GaN epitaxial layer grown on (0001) sapphire is the mixed type. In addition, to further understand the dislocation configuration on the interface of GaN/sapphire, a plane-view TEM sample of the GaN/sapphire interface was prepared. The plane-view TEM image of the GaN/sapphire interface reveals an extremely high density of kink dislocations lying on the interface, with a dislocation density of about $8\times 10^{9}$ cm-2, involving high strain and stress. A comparison of the $8\times 10^{9}$ cm-2 dislocation density with another plane-view TEM image ($6\times 10^{8}$ cm-2) near the GaN free surface revealed that approximately 7.5% of the dislocations lying on the substrate coalesce into threading dislocations generated from the interface to the GaN surface.

• 2008-10-25

著者

• Yang Jer-ren

  Institute Of Materials Science And Engineering National Taiwan University

• Yang Jer-Ren

  Institute of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617 Taiwan, R.O.C.

• Huang Shih-Yao

  Institute of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617 Taiwan, R.O.C.

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• A Transmission Electron Microscopy Observation of Dislocations in GaN Grown on (0001) Sapphire by Metal Organic Chemical Vapor Deposition
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