Origin of highly spatially selective etching in deeply implanted complex oxides

The origin of the rate of anomalously high spatially selective etching of a buried heavily implanted region in complex oxides is studied. Single-crystal LiNbO3 samples are prepared with a 0.4μm wide implanted region at depth of 10μm, using 5×1016cm−2 fluence of 3.8MeV He+, and wet etched after a low-temperature anneal. An etch-rate enhancement of 104 is found after implantation and low-temperature 175–275°C post-implantation annealing. Experiments using time-resolved optical microscopy, x-ray diffraction, and proximal-probe microscopy show that this enhancement arises from the more rapid etch-solution transport in the microdomain network formed in the implanted region after annealing.