Nanostructures of this material were identified as having high current switch ratio and ideal subthreshold slope by Cui and Lieber in 2001. Nanowire whiskers of this material are synthesized in the vapor–liquid–solid method, which employs gold nanoparticles that serve as seed nuclei. A crystalline form of this material has an indirect bandgap of 1.12 electronvolts. The process of etching this material (10[1]-5[1])in hydrofluoric acid and then reacting it with unsaturated hydrocarbons on its surface is called passivation. The Czochralski (“cho-KRAHL-skee”) process is used to achieve a high refinement purity of “nine-9s” (“nine nines”) for this material. (-5[1])Diffusion of diborane gas is used as a p-type dopant for this (10[1])material. For 10 points, what most common semiconductor is used for wafers in solar cells? (10[1])■END■ (10[3])