This heading covers :
(1) The chemical elements of Chapter 28 (for example, silicon and selenium) doped with, for example, boron or phosphorus, generally in a proportion of the order of one part per million, provided they are in the form of discs, wafers or similar forms. When in forms unworked as drawn, or in the form of cylinders or rods, they are classified in Chapter 28. (2) Chemical compounds such as cadmium selenide and sulphide, indium arsenide, etc., containing certain additives (e.g., germanium, iodine) generally in a proportion of a few per cent, with a view to their use in electronics, whether in the form of cylinders, rods, etc., or cut into discs, wafers or similar forms. The heading covers such crystals, polished or not, whether or not coated with a uniform epitaxial layer. Those more extensively worked (e.g., by selective diffusion) fall in heading 85.41 as semiconductor devices.
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