Ultrasmooth V‐Grooves in InP by Two‐Step Wet Chemical Etching

A two‐step wet chemical etching process using HBr and HBr : K 2 Cr 2 O 7 was developed in order to fabricate high‐quality V‐grooves in InP (100) wafers. A 40 nm titanium film, which was patterned by conventional photolithography and lift‐off, was used as the etching mask. The {111}A sidewalls are mirrorlike with an arithmetic average roughness of less than 0.4 nm. The tip radius of the V‐grooves is approximately 7 nm. Both values were determined by atomic force microscopy.