Al1-xScxN thin films for pyroelectric IR detectors

Aluminum nitride (AlN) is a CMOS compatible pyroelectric material with excellent dielectric and piezoelectric properties. This makes AlN an attractive candidate for MEMS applications. Compared to PZT, AlN has a lower pyroelectric coefficient but a comparable signal to noise ratio due to its superior dielectric properties. AlN can be doped with scandium, which leads to an increase of the piezoelectric coefficient [3]. As flattening of the ionic potential energy landscape implies a greater thermally induced ionic mobility, Sc doping has also the potential to improve the pyroelectric performance. The deposition of the Al1-xScxN is performed by co-sputtering and easily allows to control and vary the Scconcentration. The highest pyroelectric coefficient with a value of p = 19.3 muC/m(exp 2)K is measured at a Sc-concentration of x = 0.36, which is more than a factor of two higher compared to AlN. For pure AlN a value of p = 9.7 muC/m(exp 2)K is determined.