Abstract
The effects of carbon incorporation on the thermal stability of the interfacial TiO<sub>2</sub> layer and the electrical characteristics of Ti/TiO<sub>2</sub>/<i>n</i>-Ge contacts were investigated. The improved thermal stability and contact characteristics of Ti/TiO<sub>2</sub>/<i>n</i>-Ge contacts were characterized in terms of Schottky barrier height (SBH) and specific contact resistivity (ρ<sub><i>c</i></sub>) using the Schottky diode and circular transmission line model (CTLM). The values of SBH and ρ<sub><i>c</i></sub> increased after the rapid thermal annealing (RTA) above 550 °C. The current density–bias voltage (<i>J–V</i>) curves of the Schottky diode showed a change of contact characteristics from Ohmic-like behavior to rectifying. This thermal instability was mainly caused by the decomposition of the interfacial TiO<sub>2</sub> layer after high-temperature annealing. The structural degradation was confirmed by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) analyses. When carbon ions were incorporated into the interfacial TiO<sub>2</sub> layer, the SBH and ρ<sub><i>c</i></sub> values showed relatively stable characteristics as the RTA temperature increased up to 600 °C. The EELS mapping showed that the diffusion of oxygen from the interfacial TiO<sub>2</sub> layer was effectively suppressed thanks to the incorporation of carbon. Thus, the carbon incorporation can improve the thermal stability of the interfacial TiO<sub>2</sub> layer and the metal–insulator–semiconductor contact characteristics for Ge-based device applications.
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