Growth of porous InP: Transition from three to two dimensional structures

We present the transition state of porous InP from three to two dimensions, which is explored during electrochemical etching at constant current density in NaCl solutions on n-InP(100) wafers. The `node' of the three dimensional structure revealed by scanning electron microscopy are consistent with the oscillatory periods, and that the smooth curve is corresponding to the uniformly vertical pores along with the <;001> direction. In addition, the onset and end of the oscillations shift ahead of times with increasing current densities. Furthermore, the transition of porous InP was discussed based on the surface curvature, the diffusion-control, and the reactive heat.