  Our research group studies the deposition of high permittivity dielectrics by
a non-standard method: high-pressure sputtering. The dielectrics studied here
are gadolinium scandate deposited from dielectric targets, and gadolinium oxide
deposited from a metallic target, with an in situ plasma oxidation. The
stoichiometric gadolinium scandate presents a slight permittivity boost after
annealing, but with gadolinium-rich scandate (grown with an annealing of a
nanolaminate) the dielectric shows a high effective permittivity of 21 and no
noticeable SiO2 layer at the interface with Si. On the other hand, the stacks
fabricated with the metallic Gd target have a SiO2 interface less than 0.7 nm
thick that can be further reduced by scavenging with Ti gates. In fact, this
scavenging effect is also demonstrated for the first time with indium phosphide
substrates, obtaining a low capacitance equivalent thickness of only 2.1 nm.
