  In this paper we explore the effects of 3.5 MeV proton irradiation on
Fe(Se,Te) thin films grown on CaF2. In particular, we carry out a systematic
experimental investigation with different irradiation fluences up to 7.30x10^16
cm^-2 and different proton implantation depths, in order to clarify whether and
to what extent the critical current is enhanced or suppressed, what are the
effects of irradiation on the critical temperature, the resistivity and the
critical magnetic fields, and finally what is the role played by the substrate
in this context. We find that the effect of irradiation on superconducting
properties is generally small as compared to the case of other iron-based
superconductors. Such effect is more evident on the critical current density
Jc, while it is minor on the transition temperature Tc, on the normal state
resistivity and on the upper critical field Hc2 up to the highest fluences
explored in this work. In addition, our analysis shows that when protons
implant in the substrate far from the superconducting film, the critical
current can be enhanced up to 50% of the pristine value at 7 T and 12 K, while
there is no appreciable effect on critical temperature and critical fields
together with a slight decrease in resistivity. On the contrary, when the
implantation layer is closer to the film-substrate interface, both critical
current and temperature show a decrease accompanied by an enhancement of the
resistivity and the lattice strain. This result evidences that possible
modifications induced by irradiation in the substrate may affect the
superconducting properties of the film via lattice strain. The robustness of
the Fe(Se,Te) system to irradiation induced damage makes it a promising
compound for the fabrication of magnets in high-energy accelerators.
