Exploration of the impact of interface states density on the specific contact resistivity in TiSix/n+-Si Ohmic contacts through high-low frequency method

Abstract

In our previous work, a reduction of specific contact resistivity (ρc) in TiSix /n+-Si Ohmic contacts by ∼21% has been achieved with proper Ge Pre-amorphization Implantation (PAI). In this work, the mechanism behind such an improvement using Ge PAI is explored experimentally. Versatile characterizations including current-voltage (I- V), capacitance-voltage (C-V) measurements and cross-sectional transmission electron microscopy (XTEM) are performed and analyzed. High-low frequency method is used to extract the responsive interface states density (Dit) of TiSix /n-Si Schottky diodes with and without Ge PAI. It is demonstrated that in TiSix /n+-Si Ohmic contacts, the ρc reduction by ∼21% with Ge PAI should be ascribed to the reduction of Dit at TiSix /n-Si interface. From the distribution of Dit, it can be inferred that a part of shallow level defects can be annihilated after annealing for TiSix /n-Si with Ge PAI, but deep level traps still exist. A further discussion about the relationship between Dit and ρc is tentatively provided.