抄録
We report electronic conduction of polycrystalline and epitaxial Sr(Ti,Ru)O3 (STRO) thin films and fabrication of ferroelectric gate transistors using STRO as a channel and Pb(Zr,Ti)O3 (PZT) as a ferroelectric gate insulator. Polycrystalline and epitaxial STRO films were prepared on SiO2/Si and SrTiO3(100) by sputtering using an STRO ceramic target (Ti/Ru=40/60). Hall effect measurements revealed that polycrystalline STRO films prepared at 560 oC in a pure argon atmosphere had carrier densities of 1021-1022cm·3 and mobilities of 0.l-0.3cm2V-1s-1, respectively. When STRO films were sputtered in a mixture of argon and oxygen gases, the carrier density decreased to an order of 1020cm-3 due to an increase of Ti/Ru ratio. The mobility barely changed with an addition of oxygen. Epitaxial STRO films on SrTiO3(100) substrate showed similar carrier density and mobility to those of polycrystalline films. Hall effect measurements also indicated that polycrystalline and epitaxial STRO films had n-type conduction. Ferroelectric gate transistors with a 6nm-thick-STRO layer as a channel showed a non-volatile field effect by two opposite polarization states of PZT. The change of channel conductance was approximately 40%.
