Current-line oriented pore formation in n-InP anodized in KOH

Abstract

Electrochemically formed pores in InP in KOH switch from being crystallographically oriented (CO) to being current-line oriented (CLO) above a specific potential in both 17 mol dm-3 and 2.5 mol dm-3 KOH at a temperature of 10oC. The CLO pores formed in KOH have roughly elliptical cross sections, and are wider along the than along the perpendicular <011> direction. The CLO pores can form only when a critical porosity is reached and their formation marks the transition from porous to planar etching. Many of the features of pore formation are explained by evoking the effect that both temperature and electrolyte concentration can have on the effective diffusion length of holes at the semiconductor-solution interface.