Optical light management by self‐arrangement of inverted tetragonal pyramids on the silicon surface through copper‐assisted etching technique in a single stepInternational Journal of Energy ResearchPaperAlpan BEK / Ergi Dönerçark / Raşit TuranOptical light management by self‐arrangement of inverted tetragonal pyramids on the silicon surface through copper‐assisted etching technique in a single step