Formation of uniform and square nanopore arrays on (100) InP surfaces by a two-step etching method

Uniform and square single-crystal InP nanopore arrays have been successfully fabricated on a (100) n-InP surface by a two-step etching method. The characteristic of slow etching rates in four equivalent crystalline (011) facets of (100) n-InP in a mixture of pure HCl and pure H(3)PO(4) has been found, which is the main reason for the formation of square single-crystal InP nanopores. The distribution of nanopores can be closely associated with the distribution of carriers in the semiconductor during the electrochemical etching process. An oscillating behaviour of current has been observed, which can probably be attributed to the oscillations in concentration of the electrolyte at the pore tips caused by diffusion of the electrolyte in the nanopore channels.