Study on the Ge1–xSnx/HfO2 interface and its impacts on Ge1–xSnx tunneling transistor.

In this paper, we employ first-principle calculation to investigate the Ge1–xSnx/HfO2 interface, and then evaluate its impacts on Ge1–xSnx tunneling field-effect transistor (TFET). First-principle calculations of Ge1–xSnx/HfO2 interfaces in the oxygen-rich process atmosphere indicate that the interface states originate from the Ge and Sn dangling bond, rather than Hf-bond. The total density of state shows that there are more interface states in the semiconductor bandgap with increasing Sn fraction. By further incorporating the material and interface parameters from density functional theory calculation into advanced device simulation, the electrical characteristics of Ge1–xSnx TFET are investigated. Removing the Sn atom from the first atom layer of Ge1–xSnx in device processes is found to be beneficial to reduce the degradations. For the degradation mechanisms, the trap-assisted-tunneling is the dominant mechanism at the low Sn fraction, and enhanced Shockley-Read-Hall recombination induced by traps becomes the dominant mechanism with increasing Sn fraction. The results are helpful for the interface optimization of Ge1–xSnx TFET. [ABSTRACT FROM AUTHOR]