Study of surface morphology and optical characterization of crystalline and multi-crystalline silicon surface textured in highly diluted alkaline solutions

Abstract

In this work, alkaline texturing of (100) crystalline Si and multicrystalline Si wafers in diluted KOH solution leading to pyramidal structures is studied as a function of the etching temperature. The surface morphology is investigated using Atomic Force Microscopy and Scanning Electron Microscopy and the surface reflectance is measured by spectrophotometry in the wavelength range 200-1200 nm. It is found that etching in diluted 1% KOH solution leads to incomplete surface texturing when the etching temperature is equal to 70oC. The optimum etching temperature is found to be in the range 80-85oC which results in a minimum surface reflectance for crystalline silicon covered with an antireflection coating of 0.8%, with a uniform distribution over a wider wavelength range for samples that received a saw damage removal in 30% KOH solution prior to texturing. On the other hand, the optimum etching temperature shifts to the higher range 85-95oC for multicrystalline silicon surface with a minimum reflectance of 4.6% with ARC.