Ultrasmooth V-grooves in InP by two-step wet chemical etching

A two-step wet chemical etching process using HBr and HBr:K2Cr2O7 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 liftoff, 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.