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Piezoelectric Properties of Semiconductors

Dr I.L. Guy

June 2001

We aim to measure the piezoelectric coefficients of several compound semiconductors. The main interest is in group III-V compounds, particularly GaAs, GaN and AlN. The measurements are normally performed using an optical interferometer. A Michelson-Morley interferometer is used to measure displacements of film surface with accuracy as high as 0.3 Angstrom. This system is useful for measuring electromechanical effects in materials where the relevant coefficients are not large.

We have detected non-linearity in the electromechanical behaviour of these materials and the possibility of a significant electrostrictive contribution is also being investigated.

The piezoelectric measurements we have made to date show some variation in samples prepared by different techniques. It seems possible that this is a result of inversion domains in the material. We are currently developing a technique, based on atomic force microscopy, to produce piezoelectric maps of the surface of semiconductor films with nanometer resolution. It is hoped that this will enable simple, rapid detection of inversion domains.

Selected publications include:

1. "Extensional Piezoelectric Coefficients of Gallium Nitride and Aluminium Nitride", I.L. Guy, S. Muensit, E. M. Goldys, Applied Physics Letters {\bf 75}, p. 4133-5, (1999).
2. "Electrostriction in GaN", S. Muensit, I.L. Guy, E.M. Goldys, Appl. Phys. Lett. {\bf 75}, 3641-3, (1999)
3. "Shear Piezoelectric Coefficients of Gallium Nitride and Aluminium Nitride", S. Muensit, E. M. Goldys, I.L. Guy, Appl. Phys. Lett., {\bf 75}, p. 3965-7, (1999).
4. "Measurements of piezoelectric coefficients of nitride semiconductor films", I.L. Guy, E.M.Goldys, S. Muensit, 11-th International Semiconducting and Insulating Materials Conference Canberra Australia 3-7 July 2000.