Theoretical study on hot-carrier generation, transport and injection in TiN/TiO$_2$ junction

Abstract

Promoting performance of generation, transport and injection of hot carriers in metal/semiconductor junctions is critical for harvesting energy of hot carriers. However, the injection efficiency of hot carriers in the commonly used noble metals such as Au is extremely low, which hinders the hot carrier-based applications. Here, we predict that the plasmonic material TiN might be promising for generating, transporting and injecting hot carriers, based on first-principles calculations and Monte Carlo simulations. We found that the hot-carrier generation rate in TiN is significantly large compared to Au. The transport property of hot carriers in TiN is excellent, due to the long lifetime and mean free path. The TiN/TiO2 junction possesses very low Schottky barrier, which results in much larger injection efficiency than that in the Au/TiO2 junction. Furthermore, it is revealed that the optimal injection efficiency could be achieved in a core/shell cylindrical TiN/TiO2 junction. Our findings provide an in-depth understanding of hot-carrier generation, transport and injection, and hence are helpful for the development of hot carrier-based devices.