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Microstructure of non-polar GaN on LiGaO2 grown by plasma-assisted MBE.

Shih CH, Huang TH, Schuber R, Chen YL, Chang L, Lo I, Chou MM, Schaadt DM - Nanoscale Res Lett (2011)

Bottom Line: The already reported epi-taxial relationship and for M -plane GaN is confirmed.For the M -plane sample, the density of threading dislocations is around 1 × 1011 cm-2 and the stacking fault density amounts to approximately 2 × 105 cm-1.In the A-plane sample, a threading dislocation density in the same order was found, while the stacking fault density is much lower than in the M -plane sample.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute for Applied Physics/DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany. ralf.schuber@kit.edu.

ABSTRACT
We have investigated the structure of non-polar GaN, both on the M - and A-plane, grown on LiGaO2 by plasma-assisted molecular beam epitaxy. The epitaxial relationship and the microstructure of the GaN films are investigated by transmission electron microscopy (TEM). The already reported epi-taxial relationship and for M -plane GaN is confirmed. The main defects are threading dislocations and stacking faults in both samples. For the M -plane sample, the density of threading dislocations is around 1 × 1011 cm-2 and the stacking fault density amounts to approximately 2 × 105 cm-1. In the A-plane sample, a threading dislocation density in the same order was found, while the stacking fault density is much lower than in the M -plane sample.

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Bright field images of the A-plane GaN sample taken in the two beam condition with the  (a) and  (b). The viewing direction for these images is [0001].
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Figure 4: Bright field images of the A-plane GaN sample taken in the two beam condition with the (a) and (b). The viewing direction for these images is [0001].

Mentions: The A-plane GaN sample cut perpendicular to the [0001] direction, shown in Figure 4, displays a high density of threading dislocations. Comparing in-zone bright field images (not shown here) of the M - and A-plane films, the dislocation density of the two films is on the same order of magnitude, i.e., around 1 × 1011 cm-2. The images in Figure 4a and 4b are bright field images taken in the two beam condition with the vector parallel to the and the direction, respectively. The inset in Figure 4a displays the diffraction pattern of the GaN layer showing the growth of A-plane GaN. Dislocations that have a burgers vector parallel to can be observed in Figure 4a; these are mixed and edge threading dislocations. In Figure 4b both pure screw and edge dislocations are out of contrast since they have burgers vectors parallel to [0001] and , respectively [6], and can there-fore not be seen. Owing to the much lower density of visible dislocations in Figure 4b , we can state that most dislocations are of either edge or screw type and a minority belongs to the mixed type. In Figure 4 inversion domain boundaries appear in both pictures as straight lines as indicated. These have an inclination of 60° with respect to the interface, i.e. they lie on the other two planes of GaN.


Microstructure of non-polar GaN on LiGaO2 grown by plasma-assisted MBE.

Shih CH, Huang TH, Schuber R, Chen YL, Chang L, Lo I, Chou MM, Schaadt DM - Nanoscale Res Lett (2011)

Bright field images of the A-plane GaN sample taken in the two beam condition with the  (a) and  (b). The viewing direction for these images is [0001].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211842&req=5

Figure 4: Bright field images of the A-plane GaN sample taken in the two beam condition with the (a) and (b). The viewing direction for these images is [0001].
Mentions: The A-plane GaN sample cut perpendicular to the [0001] direction, shown in Figure 4, displays a high density of threading dislocations. Comparing in-zone bright field images (not shown here) of the M - and A-plane films, the dislocation density of the two films is on the same order of magnitude, i.e., around 1 × 1011 cm-2. The images in Figure 4a and 4b are bright field images taken in the two beam condition with the vector parallel to the and the direction, respectively. The inset in Figure 4a displays the diffraction pattern of the GaN layer showing the growth of A-plane GaN. Dislocations that have a burgers vector parallel to can be observed in Figure 4a; these are mixed and edge threading dislocations. In Figure 4b both pure screw and edge dislocations are out of contrast since they have burgers vectors parallel to [0001] and , respectively [6], and can there-fore not be seen. Owing to the much lower density of visible dislocations in Figure 4b , we can state that most dislocations are of either edge or screw type and a minority belongs to the mixed type. In Figure 4 inversion domain boundaries appear in both pictures as straight lines as indicated. These have an inclination of 60° with respect to the interface, i.e. they lie on the other two planes of GaN.

Bottom Line: The already reported epi-taxial relationship and for M -plane GaN is confirmed.For the M -plane sample, the density of threading dislocations is around 1 × 1011 cm-2 and the stacking fault density amounts to approximately 2 × 105 cm-1.In the A-plane sample, a threading dislocation density in the same order was found, while the stacking fault density is much lower than in the M -plane sample.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute for Applied Physics/DFG-Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany. ralf.schuber@kit.edu.

ABSTRACT
We have investigated the structure of non-polar GaN, both on the M - and A-plane, grown on LiGaO2 by plasma-assisted molecular beam epitaxy. The epitaxial relationship and the microstructure of the GaN films are investigated by transmission electron microscopy (TEM). The already reported epi-taxial relationship and for M -plane GaN is confirmed. The main defects are threading dislocations and stacking faults in both samples. For the M -plane sample, the density of threading dislocations is around 1 × 1011 cm-2 and the stacking fault density amounts to approximately 2 × 105 cm-1. In the A-plane sample, a threading dislocation density in the same order was found, while the stacking fault density is much lower than in the M -plane sample.

No MeSH data available.


Related in: MedlinePlus