Voltage controlled SAW velocity in GaAs/LiNbO(3)-hybrids

Area of Science:

• Solid State Physics
• Materials Science
• Acoustoelectronics

Background:

• Surface Acoustic Wave (SAW) devices leverage piezoelectric materials for acoustic wave propagation.
• Semiconductor heterojunctions offer tunable electronic properties.
• Combining these fields can lead to novel hybrid systems with enhanced functionalities.

Purpose of the Study:

• To develop a quasi-monolithical integration of semiconductor quantum well structures onto LiNbO(3) SAW devices.
• To investigate the tunability of SAW velocity by controlling the conductivity of a 2D electron system.
• To demonstrate a voltage-tunable SAW device for practical applications.

Main Methods:

• Utilized the epitaxial lift-off (ELO) technique for integrating GaAs/InGaAs/AlGaAs-quantum well structures onto LiNbO(3) substrates.
• Investigated the field-effect control of the 2D electron system's conductivity.
• Measured the resulting changes in SAW velocity and phase shift.

Main Results:

• Successfully achieved quasi-monolithical integration of quantum wells on LiNbO(3) SAW devices.
• Demonstrated that the conductivity of the 2D electron system significantly modifies SAW velocity.
• Observed a large phase shift due to the high electromechanical coupling of LiNbO(3).

Conclusions:

• The developed hybrid system enables voltage-controlled tuning of SAW properties.
• This technology paves the way for new classes of single-chip, tunable SAW devices.
• A functional voltage-controlled oscillator (VCO) was presented as a proof-of-concept.