III-V compound semiconductor supply chain — InP/GaAs substrates (AXT), epi wafers (IQE), SOI and engineered substrates (Soitec), MOCVD growth tools (Veeco, Aixtron), compound-semi foundries (Tower, Win Semi), and RF IC designers (MACOM, Qorvo, Skyworks) — enabling datacenter optical interconnect, high-frequency RF, and the ex-China supply alternatives that China's gallium and germanium export controls have made strategically critical.