Structural and chemical characterization of free-standing GaN films separated from sapphire substrates by laser lift-off

Applied Physics Letters

Volumn 77, Issue 12, 2000, Pages 1819-1821

  Stach, E A ^a   Kelsch, M ^a   Nelson, E C ^a   Wong, W S ^b   Sands, T ^b   Cheung, N W ^c  

^a LAWRENCE BERKELEY NATIONAL LABORATORY   (United States)

^b UNIVERSITY OF CALIFORNIA   (United States)

^c UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0000601114     PISSN: 00036951     EISSN: None     Source Type: Journal    
DOI: 10.1063/1.1309030     Document Type: Article

References (11)

1. M. K. Kelly, O. Ambacher, B. Dahlheimer, G. Groos, R. Dimitrov, H. Angerer, and M. Stutzmann, Appl. Phys. Lett. 69, 1749 (1996).
2. W. S. Wong, T. Sands, and N. W. Cheung, Appl. Phys. Lett. 12, 599 (1998).
3. W. S. Wong, T. Sands, N. W. Cheung, M. Kneissl, D. P. Bour, P. Mei, L. T. Romano, and N. M. Johnson, Appl. Phys. Lett. 75, 1360 (1999).
4. M. K. Kelly, R. P. Vaudo, V. M. Phanse, L. Gorgens, O. Ambacher, and M. Stutzmann, Jpn. J. Appl. Phys., Part 2 38, L217 (1999).
5. W. S. Wong, Y. Cho, E. R. Weber, T. Sands, K. M. Yu, J. Krüger, A. B. Wengrow, and N. W. Cheung, Appl. Phys. Lett. 75, 1887 (1999).
6. W. S. Wong, A. B. Wengrow, Y. Cho, A. Salleo, N. J. Quitoriano, N. W. Cheung, and T. Sands, J. Electron. Mater. 28, 1409 (1999).
7. J. C. Bravman and R. Sinclair, J. Electron Microsc. Tech. 1, 53 (1984).
8. By large-area phase contrast HREM, we mean that this is a true high-resolution micrograph containing phase information due to interference of the elastically scattered transmitted electrons. It contains atomic column information, as evident in the FFTs, and higher magnification of the image shows atomic column information. We show instead a less magnified view to emphasize the defect structures present over a larger area.
9. Although there were pockets of amorphous material present at the GaN/ sapphire interface prior to lift-off, the amorphous features in Fig. 3(a) appears along the entire edge of the sample, indicative of it being glue from the TEM sample preparation process.
10. K. T. Moore, J. M. Howe, and A. A. Csontos; Ultramicroscopy 76, 195 (1999). This difficulty arises from the competition between increasing x-ray yield and increasing x-ray absorption that occurs with increasing sample thickness. This is manifested in the spectra of Fig. 3(a) by the gradual increase in the aluminum count with increasing distance into the substrate.
11. EELS was used because it has significantly higher count rates and detectability for light elements than EDS. EELS is, however, strongly sensitive to sample thickness. Therefore, the signal from both the nitrogen and aluminum peaks tails off after the first 20 nm as the TEM sample becomes too thick.