Single crystal BaTiO 3 thin films have been transferred onto Pt-coated and Si 3 N 4 -coated substrates by the ion implantation-induced layer transfer method using H + and He + ion coimplantation and subsequent annealing. The transferred BaTiO 3 films are single crystalline with root mean square roughness of 17 nm. Polarized optical and piezoresponse force microscopy (PFM) indicate that the BaTiO 3 film domain structure closely resembles that of bulk tetragonal BaTiO 3 and atomic force microscopy shows a 90°a -c domain structure with a tetragonal angle of 0.5°-0.6°. Micro-Raman spectroscopy indicates that the local mode intensity is degraded in implanted BaTiO 3 but recovers during anneals above the Curie temperature. 1,2 In most cases, these ferroelectric thin films have a polycrystalline microstructure that degrades the piezoelectric coefficients, saturation polarization, and charge retention and causes time-dependent fatigue problems.A number of film deposition methods have been studied to fabricate high quality ferroelectric oxides. Metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD) and sol-gel synthesis processes have been used for heteroepitaxial growth of ferroelectric thin films on various substrates.3-6 However, in spite of many efforts to realize epitaxial growth on various lattice mismatched substrates, deposited thin films rarely exhibit properties comparable to those of bulk single crystals.Layer transfer is one of the most promising methods by which to realize single crystal properties in thin films and to overcome substrate-film lattice mismatch effects. Crystal ion slicing (CIS) processes have been reported for layer transfer of silicon, InP, Ge and diamond. 7,8 Recently, layer splitting and transfer of ferroelectric materials such as LiNbO 3 , LiTaO 3 , KTaO 3 , SrTiO 3 , and BaTiO 3 by sacrificial wet etching and anodic bonding methods combined with the CIS method have also been reported. 9,10 To date, characterization of both the microstructure and ferroelectric properties of transferred ferroelectric thin films as well as the principal role of the implanted gas species have not been extensively reported. Single crystal ferroelectric thin films can be used in applications such as actuator devices, monolithically integrated optical waveguides on Si-based microelectronics devices 17 /cm 2 , and 30-115 keV He + ion was subsequently implanted with a dose in the range of 5 ϫ 10 16 -1ϫ 10 17 /cm 2 . Implantation was performed at −25°C to prevent the formation of cavities during implantation. The root mean square (rms) roughness of the surface was 2.0 nm for unimplanted bulk BaTiO 3 and 2.0-3.0 nm for as-implanted BaTiO 3 . The substrates used for layer transfer were 50 nm thick low pressure CVD (LPCVD) grown Si 3 N 4 / n-Si with a surface roughness of 0.5-0.8 nm and 200 nm thick sputter-deposited Pt films on 50 nm Si 3 N 4 / Si with a surface roughness of 3.0 nm.After the implantation step, both BaTiO 3 and the substrates were cleaned by dipp...