Large photocurrent-response observed at Pt/InP Schottky interface formed on anodic porous structure

A photoelectric-conversion device—based on an InP porous structure utilizing the large surface area inside pores and the low reflectance on the porous surface—is proposed. The InP walls inside the pores are covered with thin platinum films that form a Schottky barrier yielding an electric field that separates photo carriers generated under illumination. The coverage of the platinum film and its optical reflectance depended largely on the surface morphology of the porous structure. Removal of the irregular top layer formed at the initial stage of the pore formation effectively improved the coverage of the platinum film, which showed a very low optical reflectance (i.e., below 3.2%). According to current–voltage measurements under illumination, the platinum/porous InP showed larger photocurrents and higher responsivity than those of a reference planar sample.

► A photoelectric-conversion device based on InP porous structure is proposed.
► The InP walls inside the pores are covered with thin platinum films.
► The coverage and reflectance of the Pt film depended on the InP surface morphology.
► The platinum/porous InP showed large photocurrents and high responsivity.