Metal Organic Chemical Vapor Deposition Characteristics of Germanium Precursors

Polycrystalline germanium (Ge) thin films were grown by metal organic chemical vapor deposition (MOCVD) using tetra-allyl germanium [Ge(allyl)(4)], and germane (GeH4) as precursors. Ge thin films were grown on a TiN(50 nm)/SiO2/Si substrate by varying the growth conditions of the reactive gas (H-2), temperature (300-700 degrees C) and pressure (1-760Torr). H-2 gas helps to remove carbon from Ge film for a Ge(allyl)(4) precursor but not for a GeH4 precursor. Ge(allyl)(4) exhibits island growth (VW mode) characteristics under conditions of 760Torr at 400-700 degrees C, whereas GeH4 shows a layer growth pattern (FM mode) under conditions of 5Torr at 400-700 degrees C. The activation energies of the two precursors under optimized deposition conditions were 13.4 KJ/mol and 31.0 KJ/mol, respectively.