Pulsed-laser deposition of oxides: high-T c superconductors and piezoelectrics

Abstract

Pulsed-laser deposition (PLD) is an excellent technique to grow thin films and multi-layers of complex oxide materials. We present our recent results on deposition, characterization and nano-patterning of novel oxide high-temperature superconductors (HTS) and piezoelectric materials. HTS thin films of improved superconducting properties are fabricated from ceramic targets consisting of Y 2 Ba 4 CuMO y (M = metal) nano-particles embedded in YBa 2 CU 3 O 7 (YBCO) matrix. The nano-composite ceramics are UV-laser ablated and the optical plasma emission is monitored by laser - induced breakdown spectroscopy. The HTS films reveal superconducting critical current densities that depend on target composition and are strongly enhanced as compared to phase pure YBCO films. Application of HTS layers in future nano-electronic devices requires novel techniques for nano-patterning. Masked ion-beam structuring enables the nano-patterning of YBCO thin films in a direct and single-step process. Gallium orthophosphate (GaPO 4 ) thin films and piezoelectric ZnO multi-layers are reported also. GaPO 4 is an outstanding piezoelectric material with very high transition temperature (∼ 970 °C). Epitaxial GaPO 4 films are fabricated on quartz substrates by PLD and thermal post-annealing. Long-term annealing at high temperature does not degrade the GaPO 4 films. Multi-layers of Al and Li doped ZnO are pulsed-laser deposited on various substrates and investigated for applications in thin film sensors.