Etching study of microdomains in LiNbO3 single crystals

Microdomains in LiNbO3 single crystals have been investigated in considerable detail by the etch technique. Etch features, such as etch hillocks on the negative c surface, etch pits on the positive c surface, and needle−shaped etch patterns on the Y surface, have been examined by optical and electron microscopy. The results of detailed observations of the features lead to the conclusion that a common source of these patterns is a reverse polarized needlelike microdomain, less than 1 μm in diameter and 300 μm in length, lying parallel to the c axis, namely the polarization axis of LiNbO3. Mechanical scratching on the c surface and the subsequent chemical etching produce new hillocks on the negative surface and etch pits on the positive surface. It has been proposed that the polarization reversal takes place on a microscopic scale by scratch−induced stress.