Bulk-like pentacene epitaxial films on hydrogen-terminated Si(111)

Abstract

The epitaxial growth of pentacene on hydrogen-terminated Si͑111͒ is reported. Reflection high energy electron diffraction ͑RHEED͒ revealed that the crystal packing resembles that in the bulk crystal even at a monolayer thickness, which was maintained in multilayers. A ripening effect was clearly observed by atomic force microscopy ͑AFM͒. These results are important to obtain oriented crystalline films of pentacene combined with silicon microdevices with reduced defect densities.

Temperature-dependent orientation study of the initial growth of pentacene on amorphous SiO 2 by molecular dynamics simulations

“…Our results are agreement with their calculations, what's more, we further point out beyond 290K there being another threshold substrate temperature for the re-orientation phenomena. The optimal substrate temperature range we obtained for the pentacene on a-SiO 2 substrate agrees with that found by Shimada [24], who used reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM) to reveal the epitaxial growth of pentacene on hydrogen-terminated Si(111).…”

“…A wide range of temperatures from 270 K to 600 K are set. Within the substrate temperature range, we find that there exists a transition for pentacene molecules from the normal-oriented, ordered phase to the lateral-oriented, disordered one during the deposition process and an optimal temperature range is obtained, which agrees well with the experimental study [24]. A comparison of the interactions between molecule-substrate and molecule-molecule is also made to elucidate the temperature-dependent orientation transition mechanism.…”

“…Despite the noise in the data, it is easy to see that the entire processes can be divided into three stages for the two models: I) for 270K < sub T < 350K, 24 θ increases steadily from 25° to 35°, meanwhile 30 θ keeps around 55° and there is a peak for 30 θ (69°) when sub T comes to 320K; II) for 350K < sub T < 510K, θ begin to decrease by large scale with large fluctuations until θ reach their lowest points (≈7°) at 480K and 500K, respectively, corresponding to the formation of the lateral orientation; and III) for sub T > 510K, θ recover slightly to about 15° with little fluctuations, implying the steady state of the lateral 6 orientation. The corresponding results also appear in the order parameter distributions presented in Figure 5b: during the substrate temperatures ranging from 270K to 350K, (24) OP ϕ keeps at around 0.6 after a steep rise at 300K and (30) Based on the above simulations, it is clear that the initially normal-oriented, ordered cluster will gradually transfer to the lateral-oriented, disordered one with the increase of substrate temperature. The transition can be explained using the calculated results of interaction energies, as depicted in Figure 6, which can be divided into three stages as well.…”

Shape of heteroepitaxial island determined by asymmetric detachment

“…Since Pn is known to grow in a standing-up orientation [17], an interaction between Pn molecules is stronger than that between Pn and the substrate. Let us now imagine that a Pn crystalline film is growing on a vicinal surface with a positive slope, as shown in Fig.…”

“…When they are adsorbed on a substrate, molecules can be normal or lateral to the substrate surface [18]. Pn molecules are known to grow a wetting film with the molecular long axis normal to the H-Si(1 1 1) surface, namely in a standing-up orientation [17]. Behenic acid is also known to be in a stand-up orientation but with a small tilting on a substrate.…”