Dislocation Etching Morphology on the A Plane of Sapphire Crystal

Abstract

In this work, the dislocation etching pit morphology and etching kinetics on the A‐{11true2¯0} plane of sapphire crystal (α‐Al2O3) are studied experimentally. The results show that the etch pit exhibits a subrhombic 3D morphology, which is consistent with the atom arrangement symmetry of the A plane. Further analysis shows that the two adjacent sides of the rhombic etch pits correspond to the directions [3true3¯0true1¯] and [3true3¯02], respectively; both of them are in the atomic close‐packing direction of A plane. The etch pits are controlled by a chemical reaction between Al2O3 and potassium hydroxide (KOH) with the reaction activation energy of 51.7 kJ mol−1, which is developed in a manner of kinematic wave by the step moving with a constant speed.

Molten Barium Hydroxide as Defect Selective Drop Etchant for Dislocation Analysis on Aluminum Nitride Layers

“…In particular, the dissolution of aluminum oxide can lead to an undesired change in the melt chemistry or the etching reaction. [ 29 ] Therefore, a technique is needed where the etching is confined to the Al‐polar surface only and the area to be etched can be controlled.…”