ScAlN/3C-SiC/Si platform for monolithic integration of highly sensitive piezoelectric and piezoresistive devices

Abstract

This paper reports on a platform for monolithic integration of piezoelectric and piezoresistive devices on a single chip using the ScAlN/3C-SiC/Si heterostructure. Surface acoustic wave devices with an electromechanical coupling of 3.2% and an out-of-band rejection as high as 18 dB are demonstrated using the excellent piezoelectric properties of ScAlN and low acoustic loss of 3C-SiC. Additionally, a large piezoresistive effect in the low-doped n-type 3C-SiC(100) thin film has been observed, which exceeds the previously reported values in any SiC thin films. The growth of the n-type 3C-SiC thin film was performed using the low pressure chemical vapor deposition technique at 1250 °C and the standard micro-electro-mechanical systems process is used for the fabrication of 3C-SiC piezoresistors. The piezoresistive effect was measured using the bending beam method in different crystallographic orientations. The maximum gauge factor is -47 for the longitudinal [100] orientation. Using the longitudinal and transverse gauge factors for different crystallographic orientations, the fundamental piezoresistive coefficients of the low-doped n-type 3C-SiC thin film are measured to be π 11 = (- 14.5 ± 1.3) × 10 - 11 Pa-1, π 12 = (5.5 ± 0.5) × 10 - 11 Pa-1, and π 44 = (- 1.7 ± 0.7) × 10 - 11 Pa-1,.