602 / 2019-03-15 21:01:29

Improved electrical properties of MoS2 transistor with Hf1-xTixO as gate dielectric

MoS2 transistor; Hf1-xTixO gate dielectric; mobility; Coulomb screening effect; conduction band offset;

全体主题 > Nanoelectronics

Carrier mobility of MoS2 transistor can be greatly improved by screening the Columbic scattering by a high-k gate dielectric. In this work, different-content TiO2 is incorporated into HfO2 to form Hf1-xTixO gate dielectric to investigate its effects on electrical properties of MoS2 transistor. It is found that enhanced mobility and decreased gate leakage current can be achieved by optimizing the Ti content, i.e. when using Hf0.9Ti0.1O (x = 0.1) as gate dielectric, the device exhibits the highest carrier mobility of 31.5 cm2/Vs, which is 1.3╳ improvement as compared to the sample with HfO2 as gate dielectric (24.1 cm2/Vs). The main mechanism lies in that the Hf1-xTixO has higher k value than HfO2, leading to enhanced Coulomb screening effect and thus higher carrier mobility. However, with the increase of Ti content, e.g. Hf0.85Ti0.15O (x = 0.15), the device exhibits larger off current and degraded subthreshold swing. This is probably attributed to a decreased conduction-band offset between Hf0.85Ti0.15O and MoS2, and degraded MoS2/Hf1-xTixO interface quality.