Infrared-laser based characterization of the pyroelectricity in AlScN thin-films

A measurement system for characterization of the pyroelectricity in thin- and thick-films is introduced. The system is based on a quantum-cascade infrared laser that stimulates the temperature within the sample film with variable modulation frequencies up to 120 kHz. As model material system we choose Scandium-doped Aluminum Nitride (AlScN) due to its promising piezo- and dielectric behavior as well as CMOS compatibility. We measured the pyro-electric response and its temperature characteristics. The transverse effective piezoelectric coefficient e31f is derived from the measurement of the longitudinal effective piezoelectric modulus d33 and we discuss the contribution of piezoelectric clamping to the measured pyroelectric response. Our findings are important for integration of AlScN films on exposed membranes for dense and sensitive infrared detectors.