Defect-Related Etch Pits on Crystals and Their Utilization

Etch pits could form on an exposed surface of a crystal when the crystal is exposed to an etching environment or chemicals. Due to different dissolution rates along various crystalline directions in a crystal, the dissolution process is anisotropic; hence, etch pits usually have a regular shape. Here, the morphology and origin of the regular-shaped etch pits are discussed firstly; then, factors which could affect the morphology and density of etch pits are shown; finally, the state of the art of etch pit technology and the utilization of etch pits is presented. Traditionally, etch pits are utilized to evaluate the dislocation density and some defect-related properties. Now, in the modern fabrication industries, the relationship between etch pits and defects has been utilized more skillfully. High-quality crystals can be fabricated by controlling dislocations revealed by etch pits. Meanwhile, with the as-revealed dislocation as the diffusion path of atoms, new crystals will emerge in corresponding etch pits.