Surface modifications of crystal-ion-sliced LiNbO3 thin films by low energy ion irradiations

•Single crystalline 128°Y-cut LiNbO3 thin films are fabricated on Si substrates by crystal-ion-slicing technique using BCB wafer bonding.•Low energy Ar+ irradiation is adopted to implement surface polishing on the submicron single crystalline LN thin films.•Surface damage layer produced by CIS process is removed by Ar+ irradiation.•A smooth surface of LN thin films is finally obtained by Ar+ irradiation.