Acoustic wave amplification with thin film silicon bonded on lithium niobate

Abstract

Signal processing with the use of acoustic waves is an important technology for various functions in RF systems, including matched filtering in congested parts of the frequency spectrum. In order to generate long time delays on chip required for these applications, the acoustoelectric effect offers the ability to counter acoustic propagation losses while also generating inherent non-reciprocity. In this work, we demonstrate an approach to directly bond thin film silicon from 200-mm commercial SOI wafers on X-cut lithium niobate substrates with the use of plasma surface activation. The resulting delay line devices at 410 MHz demonstrate amplification of Rayleigh waves, with a peak non-reciprocal contrast between forward and reverse traveling waves of over 25 dB/mm under continuous DC bias conditions. The demonstrated process can extend the functionality of traditionally passive piezoelectric RF microsystems.