Origins of common semiconductor materials: Which semiconductor element is industrially produced from silica sources such as sand and can also be extracted from high-silica coal fly ash?

Introduction / Context:
Silicon dominates modern electronics due to its abundance, stable oxide, and mature processing. Understanding feedstocks for semiconductor-grade silicon connects materials science with device fabrication and sustainability, including recycling industrial by-products like coal fly ash that are rich in silica.

Given Data / Assumptions:

• Question targets the typical source material for elemental silicon.
• Silica (silicon dioxide) is abundant in sand and can be present in coal fly ash.
• Additional purification steps are required for electronic-grade silicon.

Concept / Approach:

Elemental silicon is produced by reducing silicon dioxide (SiO2) in a high-temperature furnace (carbothermic reduction), yielding metallurgical-grade silicon. Further purification (for example, Siemens process) produces polycrystalline silicon for wafers. Alternative silica sources include quartz, sand, and processed fly ash, though sand/quartz are the dominant industrial sources.

Step-by-Step Solution:

Verification / Alternative check:

Industry references consistently cite sand/quartz as the primary sources. Research initiatives explore fly-ash-derived silica for value recovery, aligning with circular economy goals.

Why Other Options Are Wrong:

• Germanium: obtained from zinc ores and coal by-products but not primarily from sand/fly ash silica.
• Tin: metallic element from cassiterite, not a principal semiconductor for ICs.
• Carbon: elemental but typically not processed from silica; diamond/graphene applications differ.
• Gallium: extracted from bauxite processing and zinc ores, not from silica.

Common Pitfalls:

• Equating “made from sand” with “impure”; semiconductor-grade requires extensive purification.
• Confusing silicon (element) with silicone (polymer) or silica (oxide).

Final Answer:

silicon