S-band acoustoelectric amplifier in an InGaAs-AlScN-SiC architecture

Abstract

Here, we report on an acoustoelectric slab waveguide heterostructure for phonon amplification using a thin Al0.58Sc0.42N film grown directly on a 4H-SiC substrate with an ultra-thin In0.53Ga0.47As epitaxial film heterogeneously integrated onto the surface of the Al0.58Sc0.42N. The aluminum scandium nitride film grown directly on silicon carbide enables a thin (∼850 nm thick) piezoelectric film to be deposited on a thermally conductive bulk substrate (370 W/m K for 4H-SiC); the high thermal conductivity of the substrate, large mobility of the semiconductor (∼7000 cm2/V s), and low carrier concentration (∼5 × 1015 cm−3) yield low self-heating. A Sezawa mode with optimal overlap between the peak of its evanescent electric field and the semiconductor charge carriers is supported. The high velocity of the heterostructure materials allows us to operate the Sezawa mode amplifier at 3.05 GHz, demonstrating a gain of 500 dB/cm (40 dB in 800 μm). Additionally, a terminal end-to-end radio frequency gain of 7.7 dB and a nonreciprocal transmission of 52.6 dB are achieved with a dissipated DC power of 2.3 mW. The power added efficiency and acoustic noise figure are also characterized.