Tip-Substrate-Distance Dependent Etching Process of III-V Semiconductors Investigated by Scanning Electrochemical Microscopy

Based on the fundamentals of electrochemically induced chemical etching, the confined etchant layer technique (CELT) has proven to be a versatile electrochemical micro/nanofiabrication technique. However, the tip–substrate distance-dependent etching reaction rate and surface passivation reaction rate make it difficult to correlate these electrochemical micro/nanofabrication conditions with practical etching results. In this article, combining topography analysis of etching pits and finite element method (FEM), we investigated the effect of tip–substrate distance coupling with etching reaction kinetics (ke) and passivation reaction kinetics (kp) on the etching of III–V semiconductors. Further, the coupling relationships between tip–substrate distance and reaction kinetics are correlated to practical etching profiles. It is found that tip–substrate distance is more important for etching resolution, while ke and kp are more important for etching efficiency. For materials with small kp (i.e., n-GaAs), choosin...