The initial growth mechanism of Al2O3 using trimethylaluminum and water precursors on OH/Si(1 0 0)-2 x 1 surface were theoretically explored with SIMOMM:MP2/6-31G(d) in order to elucidate unique characteristics of OH/Si(1 0 0) surface as compared to H/Si(I 0 0). The additional surface -OH group significantly increases the thermodynamic stabilities of initial complexes and subsequent products, and it reduces the reaction barriers of the initial deposition of TMA. It also allows the ring closing reaction essentially saturating surface bonding sites in between surface and Al2O3 junction region. (c) 2006 Elsevier B.V. All rights reserved.