Real-Time Observation and Control of Pentacene Film Growth on an Artificially Structured Substrate

Rapid developments in semiconductor technology are based on the fabrication of thin layers and/or their multilayered films of semiconductor crystals. The artificially grown layers can be formed utilizing sophisticated film-growth techniques, in which film thickness, surface, and interface smoothness are controlled essentially with atomic monolayer (ML) precision. The elementary growth processes, such as nucleation, surface diffusion, or step advancement, are fully understood, [1] which assists the fabrication of high-quality films applicable to real electronic and optical devices. The formation of layers, which is homogeneous in plane, has thus been well realized and multilayered structures that exhibit horizontally homogeneous and vertically heterogeneous systems have also become possible. However, so far, film growth on artificially structured substrates has not been investigated, at least from the viewpoint of atomistic processes. This kind of film growth on the substrate, which exhibits heterogeneity within the plane, is becoming increasingly important for the construction of future nanodevices. A typical example is the fabrication of organic electronic devices, which have been studied extensively in the past decade because of their various advantages, such as low processing costs, low weight, mechanical flexibility, and ease of large-scale fabrication. [2‐4] Recently, research interest in this area has focused on organic field-effect transistors (OFETs). Pentacene (C22H14) has attracted most attention as a channel material because of a remarkably high charge-carrier mobility [5] of