Strain Engineering for Enhanced TiN/TiO₂ Hot Electron Photodetection

Metal/semiconductor heterojunctions for hot carrier photodetection have garnered significant attention. However, enhancing the quantum efficiency remains a critical challenge. Introducing lattice strain into metallic materials offers a viable approach to enhance the performance of TiN/TiO₂ hot electron photodetectors by effectively modulating their electronic structure. Herein, we investigate how strain influences the electronic structure of TiN and consequently affects the generation, transport, and injection processes of hot carriers using first-principles calculations. Subsequently, we evaluate the injection efficiency and responsivity of the TiN/TiO₂ photodetector through Monte Carlo simulations. We find that compressive strain renders the energy bands more delocalized and reduces the density of states DOS, leading to diminished hot electron generation, especially in the high-energy region above the Schottky barrier. This reduction suppresses electron-electron scattering, thereby increasing the hot electron lifetime and mean free path. Consequently, the hot electron injection efficiency is enhanced, ultimately improving the responsivity of TiN/TiO₂ photodetector by a factor of 1.3-2.4 over the incident photon energy range of 0.1-3 eV.