Method of making light trapping crystalline structures

Abstract

A method of making a crystalline semiconductor structure provides a photonic device by employing low thermal budget annealing process. The method includes annealing a non-single crystal semiconductor film formed on a substrate to form a polycrystalline layer that includes a transition region adjacent to a surface of the film and a relatively thicker columnar region between the transition region and the substrate. The transition region includes small grains with random grain boundaries. The columnar region includes relatively larger columnar grains with substantially parallel grain boundaries that are substantially perpendicular to the substrate. The method further includes etching the surface to expose the columnar region having an irregular serrated surface.