Significantly enhanced SAW transmission in voltage tunable GaAs/LiNbO3 hybrid devices

Thin GaAs quantum well structures fused onto LiNbO₃ substrates using the epitaxial lift off technology offer the possibility to control the SAW velocity via field effect. The tunability of the conductivity in the GaAs quantum well results in a large change of the SAW velocity and phase. This effect is in general accompanied by an attenuation over a small region of conductivity, decreasing the device performance. We show that a lateral modulation of the in-plane conductivity distributes the SAW attenuation over the whole voltage tuning range. Employing this technique, the maximum attenuation of the hybrid SAW device is significantly reduced. Our approach opens new possibilities for voltage controlled SAW devices. Single-chip voltage controlled SAW oscillators, variable broadband delay lines and remote SAW voltage sensors can be realized