Fabrication of Vertical and Uniform-Size Porous InP Structure by Electrochemical Anodization

A vertical porous InP structure with an aspect ratio larger than 100 was obtained by electrochemical anodization of a <111>A-oriented n-InP substrate with HCl etchant. The photoluminescence spectrum of this porous InP showed less surface recombination as well as a slight blue shift attributed to the quantum-size effect. By initiating the etching through SiO2-defined mask windows, which were prepared by electron-beam direct writing along 3 crystalline directions, a uniformly sized (around 72% within the permissible fluctuation error of about 4 nm against 100-nm-sized triangles), high-density (around 50%) structure was fabricated for the first time. These results reveal that this process is very attractive for the fabrication of high-density and low-size-fluctuation quantum-wire and -box structures.