Research Article Effect of Isopropyl Alcohol Concentration and Etching Time on Wet Chemical Anisotropic Etching of Low-Resistivity Crystalline Silicon Wafer Eyad Abdur-Rahman, 1 Ibrahim Alghoraibi, 1,2 and Hassan Alkurdi 1 1 Physics Department, Damascus University, Baramkeh, Damascus, Syria 2 Department of Basic and Supporting Sciences, Faculty of Pharmacy, Arab International University, Damascus, Syria Correspondence should be addressed to Ibrahim Alghoraibi; ibrahim.alghoraibi@gmail.com Received 4 March 2017; Accepted 28 June 2017; Published 31 July 2017 Academic Editor: Falah H. Hussein Copyright © 2017 Eyad Abdur-Rahman et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A micropyramid structure was formed on the surface of a monocrystalline silicon wafer (100) using a wet chemical anisotropic etching technique. Te main objective was to evaluate the performance of the etchant based on the silicon surface refectance. Diferent isopropyl alcohol (IPA) volume concentrations (2, 4, 6, 8, and 10%) and diferent etching times (10, 20, 30, 40, and 50 min) were selected to study the total refectance of silicon wafers. Te other parameters such as NaOH concentration (12% wt.), the temperature of the solution (81.5 ∘ C), and range of stirrer speeds (400 rpm) were kept constant for all processes. Te surface morphology of the wafer was analyzed by optical microscopy and atomic force microscopy (AFM). Te AFM images confrmed a well-uniform pyramidal structure with various average pyramid sizes ranging from 1 to 1.6 m. A UV-Vis spectrophotometer with integrating sphere was used to obtain the total refectivity. Te textured silicon wafers show high absorbance in the visible region. Te optimum texture-etching parameters were found to be 4–6% vol. IPA and 40 min at which the average total refectance of the silicon wafer was reduced to 11.22%. 1. Introduction Silicon solar cells dominate the current photovoltaic mar- ket [1] due to their advantages, including low cost, easy fabrication, and environmental friendliness [2]. Planar Si surfaces have a high natural refectivity with a strong spectral dependence [3]. In order to reduce this high refectivity and to trap the light in the solar cell, diferent surface texturing techniques have been developed over the last years [4–8] like plasma etching [9, 10], mechanical engraving [10], chemical anisotropic etching [11], laser texturing [12, 13], and reactive ion etching [14, 15]. However, the wet chemical anisotropic etching in alkaline solutions is the most common process for industrial solar cell texturing [15] because it is actually a good compromise between cost and efciency [10]. Tese solutions rely on the diference in etch rate between ⟨100⟩ and ⟨111⟩ oriented planes (Figure 1) and result in random, upright micrometer-scale pyramids on a ⟨100⟩ oriented surface. Each pyramid forces the refected ray to be incident on an adjacent pyramid and thus to undergo another refection into the wafer. Hence, light collection increases due to multiple inter- nal refections. Alkaline solutions used in anisotropic etching can be either an organic or an inorganic compound. Among all alkaline solutions, the two inorganic KOH and NaOH solutions and the organic TMAH (tetramethylammonium hydroxide) solution are the most frequently used [6]. Silicon reacts with NaOH in deionized water (DI-W) as in the following total reaction equation [7]: Si (s) +2NaOH (aq) + H 2 O (l) → Na 2 SiO 3(aq) +2H 2(g) ↑ (1) Te alkaline solution etches ⟨111⟩ planes with a very low etching rate compared with other planes, especially ⟨100⟩ planes (the etching rate ratio for ⟨100⟩ to ⟨111⟩ planes is 10∼35). Tis strong dependence of the etching rate on crystal orientation leads to the formation of 4-sided pyramidal structures that have a ⟨100⟩ base plane and ⟨111⟩ faces [16]. One problem in the texturing process is the generation of H 2 bubbles that attach to the wafer’s surface causing the Hindawi International Journal of Analytical Chemistry Volume 2017, Article ID 7542870, 9 pages https://doi.org/10.1155/2017/7542870