Demonstration of ferroelectricity in ScGaN thin film using sputtering method

It is recently found that wurtzite aluminum nitride exhibits ferroelectricity by alloying with scandium. Because its remanent polarization (P-r) is large, ScxAl1-xN has attracted much attention. Gallium nitride with similar structure and properties is also expected to show ferroelectricity. Herein, ScxGa1-xN was prepared on a silicon substrate at 673 K using the sputtering method, and its ferroelectricity was investigated. Sc0.41Ga0.59N exhibited ferroelectricity before dielectric breakdown. P-r of this film, as evaluated via positive-up-negative-down (PUND) measurement, was around 120 mu C/cm(2), which can reduce the influence of the leakage current. This was comparable to the value of ScxAl1-xN with the same internal parameter u, which is approximately estimated from the lattice constants. Moreover, in the PUND measurement, the measurement temperature dependence of E-c was observed, which was 4.3 MV/cm at 300 K and reduced to 3.2 MV/cm at 473 K.

Automated summary

Wurtzite aluminum nitride has been found to exhibit ferroelectricity when alloyed with scandium, attracting attention due to its large remanent polarization (P-r). Similar properties are expected for gallium nitride with a similar structure. Sc0.41Ga0.59N prepared on a silicon substrate using sputtering showed ferroelectricity with a P-r value of around 120 mu C/cm(2), comparable to ScxAl1-xN. Temperature dependence of coercive field (E-c) was observed in the positive-up-negative-down (PUND) measurement, decreasing from 4.3 MV/cm at 300 K to 3.2 MV/cm at 473 K.