Electrical properties and charge imbalance for Ca,Ge-substituted garnet films grown by liquid-phase epitaxy from PbO-BO fluxed melts

Abstract

Ca,Ge‐substituted garnet films show p‐type conduction when grown from melts of Ca/Ge molar ratio, R₅ parameter≡[CaO]/([CaO]+[GeO₂]) ≳0.486. n‐type conduction is observed for films grown from R₅‐parameter ?0.275 melts. Through experiments on Ge and/or Ca doping to (Y,Sm)₃(Fe,Ga)₅O₁₂ garnet films, these dopants are concluded to play important roles in the resistivity, as well as the conduction type. It is inferred that Ca content in films exceeds Ge content for p‐type Ca,Ge‐substituted garnet films and that Ge content exceeds Ca content for n‐type films. These results are obtained from measuring resistivity and the sign of the Seebeck effect for (Y,Eu,Tm,Ca)₃(Fe,Ge)₅O₁₂ garnet LPE films at room temperature. Both resistivity at melt saturation temperature and the conduction type depend on R₅‐parameter values. Low‐coercivity films are reproducibly obtained from R₅∼0.1 melts.