In the context of doping, In/Zn = 1 at.% refers to the ratio of indium atoms to zinc atoms in a given sample. This means that for every 100 atoms of zinc, there is 1 atom of indium. The discussion centers on calculating the mass of indium chloride (InCl3) required to achieve this doping level in zinc oxide. The formula suggests that the number of indium atoms as a dopant divided by the total number of zinc oxide molecules equals 1%. Understanding this ratio is crucial for precise doping in materials science. Accurate calculations are essential for achieving desired electrical and optical properties in doped zinc oxide.