First Principles Study of Electronic Properties of MoS$_{2}$/HfO$_{2}$ Interface

Monolayer MoS$_{2}$ is direct band gap two dimensional (2D) semiconductor which has been recently investigated for low-powered field effect transistors and shown promising performance of high on/off current ratio (10$^{8})$ and a carrier mobility $\sim$ 200 cm$^{2}$/Vs with a high-k gate dielectric [1]. For a detailed understanding of the MoS$_{2}$ electronic devices, it is important to examine the detailed atomic and electronic structures of the MoS$_{2}$/HfO$_{2}$ interface. We have developed a lattice matched MoS$_{2}$/HfO$_{2}$ interface model, and investigated the interface atomic structures and the corresponding electronic structures using the density functional theory (DFT) calculations. The model interface was extensively investigated as a function of oxygen and hydrogen incorporation representing different HfO$_{2}$ growth conditions on MoS$_{2}$. The interface formation energies show strong effects of interfacial oxygen content and the valence band offset. \textit{In situ} XPS study of HfO$_{2}$ ALD on MoS$_{2}$ shows that the experimental MoS$_{2}$/HfO$_{2}$ interface properties are consistent with DFT results [2]. These studies can be extended to other TMDs in an effort to identify most promising candidates for electronic device applications. \\[4pt] [1] B. Radisavljevic \textit{et}.al, \textit{Nat. Nanotechnol}. \textbf{6}, 147 (2011). \\[0pt] [2] S. McDonnell \textit{et}. al. \textit{ACS Nano}~\textbf{(}Just Accepted).