Piezoelectric properties of III-V nitrides

Pao Yue-kong Library Electronic Theses Database

Piezoelectric properties of III-V nitrides

 

Author: Lueng, Chiu-ming
Title: Piezoelectric properties of III-V nitrides
Degree: M.Phil.
Year: 1999
Subject: Aluminum nitride
Gallium nitride
Thin films
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Applied Physics
Pages: vii, [156] leaves : ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1489835
URI: http://theses.lib.polyu.edu.hk/handle/200/581
Abstract: The main objective of this work is to measure the piezoelectric coefficients of III-V nitride thin films, namely aluminum nitride (AIN) and gallium nitride (GaN), by an interferometric technique. The nitride films were grown on Si substrates by Molecular Beam Epitaxy (MBE) and were characterized by Rutherford Backscattering Spectrometry (RBS) and X-ray Diffraction (XRD). Through these measurements, the nitride films were found to consist of mainly a hexagonal wurtzite structure. In order to grow epitaxial gallium nitride film on silicon, an aluminum nitride buffer layer is often needed, hence, some of the samples we measured are GaN/AIN/Si composite films. When a voltage is applied to a multilayer thin film, the voltage drop across each layer is determined by the ratio of the resisitivity and permittivity of the individual layer. A method to estimate the voltage drop across each layer as a function of frequency is described and used to evaluate the voltage drop across each piezoelectric layer. A single beam Mach-Zehnder type heterodyne interferometer was used to measure the displacements induced in the piezoelectric AIN and GaN samples. Using the voltage drop estimated above, the d33 and d31 coefficients of AIN were found to be (5.10 +- 0.1) pmV-1 and (2.55 +- 0.1) pmV-1 , respectively and the d33 and d31 coefficients of GaN were found to be (2.60 +- 0.1) pmV-1 and (1.30 +-0.1) pmV-1, respectively. By collating data in the literature, together with the measured d33 and d31, computer programs were compiled to calculate the velocity curves, power flow angles and electromechanical coupling coefficients in AIN, GaN, GaAs and ZnO. These results will be used for our future work in designing surface acoustic wave (SAW) devices based on these materials.

Files in this item

Files Size Format
b14898354.pdf 3.957Mb PDF
Copyright Undertaking
As a bona fide Library user, I declare that:
  1. I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
  2. I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
  3. I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.

     

Quick Search

Browse

More Information