Unintentionally doped spharelite structure BP layer grown directly on the (111)-Si substrate by an atmospheric pressure metalorganic chemical vapor deposition (MOCVD) was characterized by means of transmission electron diffraction (TED) technique. By the analysis of TED pattern from the BP layer, the epitaxial relationship was confirmed as (111), <110>-Si//<111>, [110]-BP. The (111)-BP layer was found to be made through the aggregation of (111)-BP domains oriented in the <110>-direction of the Si substrate. In the (111)-BP layer, {111}-twins bound on the {111}-BP planes aligned to [10-1]-, [-110]-, or [0-11]-Si were involved. The hetero-epitaxial BP layer was considered to grow up on the (111)-Si through the aggregation of the twinned (111)-BP domains. (C) 2004 Elsevier B.V. All rights reserved.