Micro/nanopipes are linear defects along the c-axis of hexagonal polytypes of SiC and GaN that are currently the focus of much attention. It has been shown that these defects can be very detrimental to the electronic properties of devices manufactured from, at least, 6H-SiC. In this paper, the origin of these defects is discussed in terms of Frank’s theory  that dislocations will have a hollow core when their Burgers vector is large. Two fundamental issues about such dislocations are addressed: their formation along the c-axis of the crystal, and their stability despite their large Burgers vectors . The proposed model is based on the mosaic structure of sublimation-grown 6H- or 4H-SiC, and VPE-grown 2H-GaN on sapphire substrates. The presence of unit c-axis screw dislocations is attributed to the accommodation of low-angle twist boundaries in the mosaic structure. The formation of superscrew dislocations with large Burgers vector, which empty their cores to reduce the excessive strain energy there, is shown to be the result of 3c screw dislocations in the axis of triple junctions which “getter” the neighboring unit dislocations and simultaneously increase their diameter. The predictions of the model are compared with available data in the literature, and suggestions are made for the decrease of nano/micropipe density.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
F. C. Frank, Acta Cryst. 4, 497–501 (1951).
P. Pirouz, Phil. Mag. A (1998). In press.
Y. M. Tairov and V. F. Tsvetkov, J. Crystal Growth 43, 209–212 (1978).
P. G. Neudeck and J. A. Powell, IEEE Electron Device Lett. 15, 63–65 (1994).
W. Qian, M. Skowronski, K. Doverspike, L. B. Rowland and D. K. Gaskill, J. Crystal Growth 151, 396–400 (1995).
W. Qian, G. S. Rohrer, M. Skowronski, K. Doverspike, L. B. Rowland and D. K. Gaskill, Appl. Phys. Let. 67, 2284–2286 (1995).
J. W. Yang, SiC: Problems in Crystal Growth and Polytypic Transformation, Ph. D. Thesis, Case Western Reserve University, 1993.
J. Giocondi et al., Mat. Res. Soc. Symp. Proc. 423, 539–544 (1996).
Z. Lilienthal-Weber et al., Phys. Rev. Lett. 79, 2835–2938 (1997).
S. G. Müller, R. Eckstein, W. Hartung, D. Hofmann, M. Kölb, G. Pensl, E. Schmitt, E. J. Schmitt, A. D. Weber and A. Winnacker, Materials Science Forum 264–268, 33–36 (1998).
A. R. Verma, Crystal Growth and Dislocations, (Butterworths, London, 1953).
Y. Inomata, H. Komatsu, M. Mitomo and Z. Inoue, J. Crystal Growth 2, 322–323 (1968).
P. Krishna, S.-S. Jiang and A. R. Lang, J. Crystal Growth 71, 41–56 (1985).
D. L. Barrett, J. P. McHugh, H. M. Hobgood, R. H. Hopkins, P. G. McMullin, R. C. Clarke and W. J. Choyke, J. Cryst. Growth 128, 358–362 (1993).
H. M. Hobgood, D. L. Barret, J. P. McHugh, R. C. Clarke, S. Sriram, A. A. Burk, J. Greggi, C. D. Brandt, R. H. Hopkins and W. J. Choyke, J. Cryst. Growth 137, 181–186 (1994).
M. Dudley, S. Wang, W. Huang, C. H. Carter, Jr., V. F. Tsvetkov and C. Fazi, J. Phys. D - Applied Physics 28, A63–A68 (1995).
F. C. Frank, Disc. Faraday Soc. 5, 48–54 (1949).
W. R. L. Lambrecht et al., Phys. Rev. B 44, 3685–3694 (1991).
K. Kim, W. R. L. Lambrecht and B. Segall, Phys. Rev. B 53, 16310–16326 (1996).
K. Kim, W. R. L. Lambrecht and B. Segall, Phys. Rev. B 56, 7018–7019 (1997).
W. R. L. Lambrecht and B. Segall, Mat. Res. Soc. Symp. Proc. 242, 367–372 (1992).
W. R. L. Lambrecht and B. Segall, Phys. Rev. B 48, 17841 (1993).
S. Amelinckx, in Dislocations in Particular Solids, edited by F. R. N. Nabarro (North-Holland Publishing Company 2, Chapter 6, Amsterdam, 1979), pp. 67–460.
P. Pirouz, Materials Science Forum 264–268, 399–408 (1998).
W. T. Read, Jr., Dislocations in Crystals, (McGraw-Hill, New York, 1953).
R. C. Glass, L. O. Kielberg, V. F. Tsvetkov, J. E. Sundgren and E. Janzén, J. Crystal Growth 132, 504–512 (1993).
D. Kapolnek et al., Appl. Phys. Lett. 67, 1541–1543 (1995).
B. Heying et al., Appl. Phys. Lett. 68, 643–645 (1996).
H. Amano, T. Takeuchi, H. Sakai, S. Yamaguchi, C. Wetzel and I. Akasaki, Materials Science Forum 264–268, 1115–1120 (1998).
X. H. Wu et al., Jpn. J. Appl. Phys. 35, L1648–L1651 (1996).
F. R. Chien, X. J. Ning, S. Stemmer, P. Pirouz, M. D. Bremser and R. F. Davis, Appl. Phys. Lett. 68, 2678–2680 (1996).
W. Qian et al., Appl. Phys. Let. 66, 1252–1254 (1995).
X. J. Ning, F. R. Chien, P. Pirouz, J. W. Yang and M. Asif Khan, J. Mater. Res. 11, 580–592 (1996).
X. H. Wu, L. M. Brown, D. Kapolnek, B. Keller, S. P. Denbaars and J. S. Speck, J. Appl. Phys. 80, 3228–3237 (1996).
About this article
Cite this article
Pirouz, P. The Origin of Nanopipes and Micropipes in Non-Cubic GaN and SiC. MRS Online Proceedings Library 512, 113–118 (1998). https://doi.org/10.1557/PROC-512-113