NH4OH-B Silicon Texturing of Periodic V-Groove Channels, Upright, and Inverted Pyramids Structures

Periodic V-grooves channels, upright, and inverted pyramids structures were texturized on monocrystalline silicon (c-Si) substrates using ammonium hydroxide (NH4OH) solution. This cheap and CMOS compatible etching solution aims at the integration of circuits with photovoltaic (PV) cells for monolithic purposes. To obtain these structures, lithographed silicon dioxide (SiO2) patterns were used to delimit the c-Si surface regions to be etched by the NH4OH solution. After the SiO2 removal, a scanning electron microscopy images of the surface of the samples showed that the NH4OH etch exposed the < 111 > facets, outlined by the SiO2 patterns, creating periodic V-groove channels, inverted, and upright pyramids structures with depths of 5.9 +/- 0.1, 5.7 +/- 0.4, and height of 6.9 +/- 0.1 mu m, respectively. These ordered structures reduced a polished c-Si control sample reflectance by 57.6 +/- 0.1%, 53.3 +/- 0.1%, and 51.6 +/- 0.1%, measured by a spectrophotometer with integrating sphere and having reflectance values of 16.5%, 18.2%, and 18.9%, respectively. These results indicate that the etched periodic structures using a cheap and CMOS compatible NH4OH solution, increases the c-Si light trapping, by reducing its reflectance for values lower than 20%, which could be used to increase the light absorption on PV cells.

Automated summary

The study involved texturization of monocrystalline silicon substrates using ammonium hydroxide solution to create periodic V-grooves channels, inverted, and upright pyramids structures, which reduced reflectance and increased light trapping capability, potentially enhancing light absorption in photovoltaic cells.