Fig. 1.
The position-dependent E2 (high) peak values of Raman spectra. The solid line shows the stress-free frequency of 657.4 cm-1 [17].
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| Citation: |
Maosong Sun, Jicai Zhang, Jun Huang, Xuewei Li, Linjun Wang, Xuehua Liu, Jianfeng Wang, Ke Xu. Influence of thickness on strain state and surface morphology of AlN grown by HVPE[J]. Journal of Semiconductors, 2016, 37(12): 123001. doi: 10.1088/1674-4926/37/12/123001
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M S Sun, J C Zhang, J Huang, X W Li, L J Wang, X H Liu, J F Wang, K Xu. Influence of thickness on strain state and surface morphology of AlN grown by HVPE[J]. J. Semicond., 2016, 37(12): 123001. doi: 10.1088/1674-4926/37/12/123001.
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Influence of thickness on strain state and surface morphology of AlN grown by HVPE
DOI: 10.1088/1674-4926/37/12/123001
More Information
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Abstract
AlN thick films were grown on c-plane sapphire substrates by hydride vapor phase epitaxy at high temperature. The evolution of the strain state and crystal quality of AlN with increase of thickness were investigated by transmission electron microscopy, field-emission scanning electron microscopy, Raman spectra and atomic force microscopy (AFM). As the thickness increased, the stress in the epilayers decreased gradually, which was attributed to the reaction of dislocations at the first several microns in thickness. When the thickness was more than 20 μm, the stress was almost fully relaxed due to the formation of cracks. Wet etching experiments indicated that the dislocation density decreased with the increase of thickness. The AFM images showed that the density of dark spots on the surface obviously decreased and the atomic steps became straight as the thickness increased.-
Keywords:
- AlN,
- HVPE,
- surface morphology,
- strain state
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References
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