Electrochemical etching has been proven to be a highly effective method for the removal of GaN materials. In this work, the material removal mechanisms in electrochemical-enhanced polishing process are studied from two aspects: carrier behavior and mechanical removal. It is found that the distribution of carriers can be altered along the polar plane by the electric field during electrochemical etching and will not recover spontaneously. A layer of excess carriers would accumulate on the Ga-face after electrochemical etching and cause severe surface oxidation during sample preservation. Additionally, it is revealed that the etched surface morphology can be divided into two types: protrusions and pits, depending on the excessive carrier density. Mechanical polishing is conducted on the pre-etched and non-etched surface, respectively. The pre-etched surface demonstrates better ductility than that of the non-etched surface owing to the formation of porous structure during electrochemical etching. The surface quality is also desirable which is confirmed by the photoluminescence (PL) spectra. The electrochemical etching-enhanced polishing can be considered as a semi-final processing technique that efficiently removes the damaged layer and reduces the surface roughness to sub-nanometer level.

电化学蚀刻已被证明是去除 GaN 材料的高效方法。本文从载流子行为和机械去除两个方面研究了电化学增强抛光过程中的材料去除机制。发现在电化学刻蚀过程中，电场可以改变载流子的分布沿极平面，并且不会自发恢复。电化学蚀刻后，Ga 面上会积累一层多余的载流子，并在样品保存过程中导致严重的表面氧化。此外，还表明蚀刻表面形态可分为两种类型：突起和凹坑，这取决于载流子密度过高。分别对预蚀刻和未蚀刻的表面进行机械抛光。由于在电化学蚀刻过程中形成多孔结构，预蚀刻表面比未蚀刻表面表现出更好的延展性。光致发光 (PL) 光谱证实了表面质量也是可取的。电化学蚀刻增强抛光可以被认为是一种有效去除损伤层并将表面粗糙度降低到亚纳米级的半成品加工技术。