Sputtered multicomponent amorphous dielectrics for transparent electronics

In this work, we present the structural and electrical properties of HfO2, HfO2 + SiO2, and HfO2 + Al2O3 dielectric composite layers deposited by sputtering without any intentional substrate heating. The films were deposited on glass and (100) crystalline silicon (c-Si) substrates from ceramic targets by using argon (At) and oxygen (O-2) as sputtering and reactive gases, respectively. The incorporation Of SiO2 and Al2O3 into hafnia was obtained by co-sputtering and it was controlled by adjusting the ratio of r.f. power applied between the targets. The HfO2 films present a microcrystalline structure, when deposited at room temperature (RT). The lowest leakage current in c-Si MIS (Metal-Insulator-Semiconductor) structures (below 10(9) A/cm(2) at 10 V on films with a thickness around 180 nm) was obtained for an Ar/O-2 ratio of 14:1 sccm, and further increase in O-2 flow does not enhance the electrical characteristics. The co-deposition Of SiO2 or Al2O3 with hafnia has a strong influence on the structure of the resulting films since they become amorphous. The leakage current in MIS structures incorporating these multi-component dielectrics is reduced at least by a factor of 2, which is accompanied by an increase on the band gap. The dielectric constant is decreased due to the lower values for SiO2 and Al2O3, (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim