Surface acoustic wave properties of aluminum gallium arsenide

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Abstract
Surface acoustic wave (SAW) properties are measured for {100}-cut, 〈100〉-propagating aluminum gallium arsenide (AlxGa1−xAs) with x=0.2 and 0.4. The parameters used to characterize these properties are SAW velocity, SAW attenuation, and piezoelectric coupling coefficient. The measured velocities are found to be substantially higher than those on GaAs in agreement with the theoretical predictions of Adachi. The attenuation is close to the corresponding attenuation on GaAs which is approximately 1 dB/μs. The piezoelectric coupling coefficient is measured using two independent methods and is found to be significantly higher than that of GaAs. This means that the transduction of energy from electrical to acoustical is more efficient and hence acoustic charge transport devices on AlxGa1−xAs substrates will require considerably less rf drive power. An extensive literature search has revealed no previous work, theoretical or experimental, characterizing attenuation or piezoelectric coupling of SAW on AlxGa1−xAs. The velocity has been predicted by Adachi based on a model formulated by Keyes, and has been measured by Sapriel, but the measured velocities reported herein correspond to the predicted values much better than the values measured by Sapriel. The measurement technique described has not, to the authors’ knowledge, been previously used for measurement of the piezoelectric coupling coefficient, and represents a convenient method of obtaining the SAW parameters experimentally.