Jinho Oh, Heedo Na, In-Su Mok, Jonggi Kim, Kyumin Lee, Hyunchul Sohn.
Applied Physics A, September 2012, Volume 108, Issue 3, pp 679-684.
Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749, Republic of Korea.
In our study, the physical properties of (TiO2) x (SiO2)1−x , including band-gap, band-offset, and thermal stability and the electrical properties of band-engineered SiO2/(TiO2) x (SiO2)1−x tunnel barrier stacks, including the tunneling current and charge-trapping characteristics for applications to nonvolatile memory devices were investigated. It was observed that the band-gap and band-offset of (TiO2) x (SiO2)1−x can be controlled by adjustment in the composition of the (TiO2) x (SiO2)1−x films. Ti-silicate film with TiO2:SiO2 cycle ratio of 1:5 was maintained in an amorphous phase, even after annealing at 950 °C. The tunneling current of the band-engineered SiO2/(TiO2) x (SiO2)1−x stacked tunnel barrier was larger than that of a single SiO2 barrier under a higher external bias, while the tunneling current of a SiO2/(TiO2) x (SiO2)1−x stacked tunnel barrier under a lower external bias was smaller. Charge-trapping tests showed that the voltage shift for SiO2/(TiO2) x (SiO2)1−x is slightly larger than that for single SiO2.