Surface Acoustic Wave Devices on Gallium Arsenide

Abstract

Perspectives for application of gallium arsenide (GaAs) crystals and their epitaxial wafers to the design of surface acoustic wave (SAW) devices, used for the radio signal processing, are reviewed. Characteristics of normal and leaky SAWs on different GaAs crystallographic cuts are presented. It is shown that leaky SAW, propagating in the [110] direction on the (112) cut features negligible attenuation and acoustoelectrical characteristics, suitable for the design of SAW devices. The re-sults, obtained exploring the SAW excitation and reception in GaAs wafers with submicrometre n-GaAs epitaxial layers, using aluminum interdigital transducers (IDT), forming the Schottky contact with n-GaAs, are discussed. The characteristics of linear and non-linear operation of those IDT are presented. Possibilities of operating an electrically controllable radio sig-nal phase shifter are demonstrated. It is discovered that an IDT with Schottky contacts, while working in non-linear regime simultaneously with SAW excitation, operates like a radio signal frequency multiplier. It is obtained experimentally that when two signals which frequency combination (sum or difference of frequencies) is within IDT pass band are fed, SAW are excited rather effectively. The results presented are useful for the design of integ-rated SAW and semiconductor electronic devices on the epitaxial GaAs wafers.