Investigation of terbium scandate as an alternative gate dielectric in fully depleted transistors

Terbium scandate thin films were deposited by e-gun evaporation on (100) silicon substrates. Rutherford backscattering spectrometry and x-ray diffraction studies revealed homogeneous chemical compositions of the films. A dielectric constant of 26 and $CV-$curves with small hystereses were measured as well as low leakage current densities of $<1nA/cm2$⁠. Fully depleted $n$-type field-effect transistors on thin silicon-on-insulator substrates with terbium scandate gate dielectrics were fabricated with a gate-last process. The devices show inverse subthreshold slopes of 80 mV/dec and a carrier mobility for electrons of $225cm2/V∙s$ was extracted.