A Cost-Effective Approach for Micro-Texturing of Silicon Using KOH for Solar Cell Devices

Wet etching of Si{100} in alkaline solutions typically produces pyramidal/hillock structures bounded by {111} planes and their vicinal counterparts. These geometrical structures act as efficient light-trapping structures, thereby enhancing solar cell efficiency. In this work, the influence of etchant concentration and etching temperature on the surface texturing of Si{100} in potassium hydroxide (KOH) was systematically investigated with the aim of reducing texturing costs by minimizing etchant usage and processing time in an additive-free approach. KOH concentration was varied from 0.1 to 1.0 wt% in 0.1 wt% increments at a fixed temperature of 70°C for durations ranging from 5 to 40 minutes at 5-min intervals. Among all tested concentrations, 0.5 wt% KOH produced the most favorable surface morphology, exhibiting high structural density and uniformity, as confirmed by scanning electron microscopy. This concentration also yielded the lowest solar-weighted reflectance (Rsw) of 11.8%, measured using a UV/Vis spectrophotometer equipped with an integrating sphere. Based on this result, 0.5 wt% KOH was selected for temperature-dependent studies. The etching temperature was varied from 70 to 95℃, in 5°C increments, with samples collected every 2 min up to 12 min. The lowest Rsw of 11.3% was achieved at 85°C for 10 min.