Critical thickness for dislocation generation in epitaxial piezoelectric thin films

Abstract

Dislocations form in epitaxial thin films above a critical thickness, when the stress due to the film–substrate mismatch becomes excessive. This phenomenon has been extensively investigated in non-piezoelectric thin films. In piezoelectric films, the mismatch strain field and the electric field are coupled, and the critical thickness depends on an extra physical variable: the electric field. In this paper, the critical thickness for dislocation formation in a piezoelectric film is derived. The dependence of the critical thickness on the piezoelectric properties of the Al _x Ga_{1− x} N/GaN system is then discussed.

Acknowledgements

The authors would like to thank Professor Hanchen Huang of RPI and Professor T.-Y. Zhang of The Hong Kong University of Science and Technology for stimulating discussions. This project was supported by grants from the Research Grants Council of the Hong Kong Special Administrative Region (PolyU 5173/01E and 1/99C), the National Science Foundation of China (10172030, 50232030) and Heilongjiang Province Natural Science Foundation.

Notes

† On leave from Harbin Institute of Technology, Harbin, PR China. Email: [email protected].

Additional information

Notes on contributors

Biao Wang†

† On leave from Harbin Institute of Technology, Harbin, PR China. Email: [email protected].