Selective porosification of n-InP(100) after focused ion beam implantation of Si⁺⁺

Selective pore formation can be electrochemically initiated on n-type InP(100) on presensitized surfaces. To create this presensitization, defect patterns were written into the surface by focused ion beam (FIB) implantation of Si⁺⁺. These implant sites represent initiation sites for pore growth or for selective material dissolution in the patterns, if anodic polarization is carried out positive to the pore formation potential (PFP) of the defective surface but cathodic to the PFP of the intact surface. A variety of internal and external factors were found to influence the selectivity of the process. Parameters that significantly affect the morphology are polarization voltage, implantation dosage, the time and the anion present in the electrolyte. In the present work it is shown, that pore formation in 1 M HF only occurs for a small potential range and a certain dosage range of the implanted Si⁺⁺ ions. At other potentials or dosages, a homogenous dissolution of the implanted patterns takes place. Apart from direct selective porosification of InP surfaces, the process described can be used for a selective surface patterning.