Ion implantation induced resonant states for enhanced thermoelectric response in Sb2Te3 thin films

Precise control of electronic structure remains a central challenge in thermoelectric thin films. Here, we demonstrate that ion implantation provides a controllable route to engineer electronic states in Sb2Te3 thin films. By introducing Ni ions with tunable dose, localized states are formed near the Fermi level, leading to a significant modification of the electronic structure. Notably, the Seebeck coefficient is enhanced despite an increase in carrier concentration, deviating from the conventional trade-off behavior in degenerate semiconductors. The optimal sample achieves a Seebeck coefficient of 160.42 μV K−1 and a power factor of 2.95 mW m−1 K−2 at 575 K. Combined transport analysis and first-principles calculations reveal that this behavior originates from implantation-induced resonant states, which increase the density of states near the Fermi level and enhance the carrier effective mass. These results demonstrate that ion implantation enables non-equilibrium band structure engineering in thermoelectric thin films.