Atomic Structure Method for the Calculation of Anisotropic Wet Etching Rate of Sapphire Crystal

This paper presents an atomic structure method to calculate anisotropic wet etching rates of sapphire crystal planes for the first time. Each sapphire crystal plane can be regarded as composed of three crystal plane unit A
0
, B
0
and C
0
in different combinations based on the distribution of atom types on the surface sites of each crystal plane at
$< 11\bar{2}0 >$
direction. The wet etching rates of each crystal plane can be calculated accurately by analyzing the wet etching process of sapphire crystal planes with the step flow mechanism. The wet etching rates calculated by this method is in good agreement with the experimental etch rates, which demonstrates the validity of the proposed method.