Patterned arrays of porous InP from photolithography and electrochemical etching

Patterned arrays of porous InP have been produced using electrochemical etching method at room temperature in combination with photolithography. n-type InP wafers with (001) orientation were used as the anode, and gold was used as the cathode. The porous structure was produced in either aqueous HCl or a mixture of HCl and HNO3 with a voltage bias ranging from 2 to 10 V. Alternating stripes of porous and nonporous InP have been fabricated on an InP substrate by etching a masked sample. Surface morphology measurements and cross sectional analysis of the porous layer have been conducted using atomic force microscopy and scanning electron microscopy. Photoluminescence from the porous surface shows a significant suppression of the interband transition. An energy barrier at the porous/bulk InP interface, identified from conductance measurements, is proposed to arise from the effect of surface states. (C) 2003 American Institute of Physics.