Schottky barrier heights of tantalum oxide, barium strontium titanate, lead titanate, and strontium bismuth tantalate

The Schottky barrier heights of various metals on the high permitivity oxides tantalum pentoxide, barium strontium titanate, lead zirconate titanate, and strontium bismuth tantalate have been calculated as a function of the metal work function. It is found that these oxides have a dimensionless Schottky barrier pinning factor S of 0.28-0.4 and not close to 1 because S is controlled by Ti-O-type bonds not Sr-O-type bonds, as assumed in earlier work. The band offsets on silicon are asymmetric with a much smaller offset at the conduction band, so that Ta2O5 and barium strontium titanate are relatively poor barriers to electrons on Si. © 1999 American Institute of Physics.

Schottky barrier heights of tantalum oxide, barium strontium titanate, lead zirconate titanate and strontium bismuth tantalate

Schottky barrier heights of various metals on tantalum pentoxide, barium strontium titanate, lead zirconate-titanate and strontium bismuth tantalate have been calculated as a function of metal work function. These oxides have a dimensionless Schottky barrier pinning factor, S, of 0.28 - 0.4 and not close to 1, because S is controlled by the Ti-O type bonds not Sr-O type bonds, as assumed previously. Band offsets on silicon are asymmetric with much smaller offset at the conduction band, so that Ta2O5 and barium strontium titanate (BST) are relatively poor barriers to electrons on Si.

Carbon nanotube Schottky diode and directionally dependent field-effect transistor using asymmetrical contacts

We demonstrate the fabrication and operation of a carbon nanotube (CNT) based Schottky diode by using a Pd contact (high-work-function metal) and an Al contact (low-work-function metal) at the two ends of a single-wall CNT. We show that it is possible to tune the rectification current-voltage (I-V) characteristics of the CNT through the use of a back gate. In contrast to standard back gate field-effect transistors (FET) using same-metal source drain contacts, the asymmetrically contacted CNT operates as a directionally dependent CNT FET when gated. While measuring at source-drain reverse bias, the device displays semiconducting characteristics whereas at forward bias, the device is nonsemiconducting. © 2005 American Institute of Physics.