Temperature Dependence of the Pyroelectric Coefficient of AlScN Thin Films

摘要

The piezoelectric and pyroelectric properties of aluminum nitride (AlN) canrnbe further enhanced by alloying AlN with scandium nitride (ScN). However,rnwhile the pyroelectric effect can strongly affect the performance of electroacousticrndevices such as surface acoustic wave (SAW) resonators, thernpyroelectric properties of aluminum scandium nitride (AlScN) and theirrnthermal dependence are not well known. In this work, the crystallographic,rnmicrostructural, and pyroelectric properties of 900nm thick pyroelectricrnAl_(1-x)Sc_xN thin films (x=0 to 0.3) are investigated. All films have wurtzitetyperncrystal structure and are highly c-axis oriented. The pyroelectricrncoefficient in the temperature range of 20–80 ℃ is determined by measuringrnthe generated current as a function of sinusoidal temperature excitation. Therneffective pyroelectric coefficient of AlScN increases by approximately 85% inrnthe investigated composition range. Moreover, no temperature dependence ofrnthe effective pyroelectric coefficient is observed for all samples. The increasernof the effective pyroelectric coefficient is explained qualitatively by consideringrnthe contribution of primary and secondary pyroelectric effect as well asrnthe substrate clamping.