Si-integrated lanthanide-doped ferroelectrics for a photomemory based on a photochromic reaction

We describe a Si-integrated photochromic photomemory based on lanthanide-doped ferroelectric Na_0.5Bi_2.5Nb₂O₉:Er³⁺ (NBN:Er) thin films. We show that upconversion emission can be effectively modulated by up to 78% through the photochromic reaction. The coupling between lanthanide upconversion emission and the photochromic effect ensures rewritable and nondestructive readout characteristics. Moreover, integrating photochromic thin films with Si would benefit from its compatibility with the mature complementary metal-oxide semiconductor (CMOS) technique. These results demonstrate the opportunity to develop more compact photochromic photomemories and related photonic devices.