Si-integrated ultrathin films of phase-pure Y3Fe5O12 (YIG) via novel two-step rapid thermal anneal

ABSTRACTTraditional one-step annealing of ultrathin amorphous Y–Fe–O films on Si has been reported to yield ‘incomplete crystallization’. Here, it is shown that films produced by standard anneals (e.g.: 800°C, 3 min) actually contain yttrium iron garnet (YIG) crystallites in a nanocrystalline non-garnet matrix. During in situ TEM laser annealing, a low-temperature pre-anneal enabled subsequent YIG crystallization at velocities of 280 nm/s that prevented the formation of the nanocrystalline matrix. From these results, a two-step rapid thermal anneal was identified (400°C, 3 min; 800°C, 3 min) that successfully produces phase-pure garnet films on SiO2 on Si.