Temperature dependence of the growth front roughening of oligomer films

Abstract

Growth front roughening characteristics of vacuum deposited pentamer 2,5-di-n-octyloxy-1,4-bis[4-(styryl)styryl]-benzene oligomer thin films, onto silicon substrates, strongly depend on the substrate temperature in the range ∼20 °C–100 °C. The measured roughness exponents H increase from H≈0.4 at low substrate temperatures where growth is dominated by vacancy formation, to H≈0.7–0.8 at elevated temperatures where diffusive growth takes place. Moreover, the root-mean-square roughness amplitude and the correlation length evolve with temperature closely as an Arrhenius process with activation barrier comparable to molecule transnational and rotational barriers on oligomer surfaces.

Intrinsic anomalous surface roughening of TiN films deposited by reactive sputtering

“…22 In our experiments, P * ͑h͒ becomes more asymmetric as growth proceeds ͑not shown͒, which is consistent with the fact that these terms dominate the growth evolution for longer growth times.…”

Monte Carlo simulation of vapor deposition polymerization

“…This indicates that short chains are formed at low temperatures and longer chains are generated at higher temperatures. Recently, several research groups have also measured the surface roughness evolution for polymer film growth [5][6][7]. Most experiments indicate that surface roughness increases with increasing substrate temperature, which is consistent with our simulation results.…”

“…One outstanding outcome of the dynamic scaling hypothesis is the existence of universal scaling exponents which depend on certain symmetries and the dimensionality of the system, but not on the detailed interactions. Recent experimental investigations on polymer film growth have shown quite different scaling exponents, but the surface RMS roughness w increased with the substrate temperature [5][6][7]. Despite the difference in the detailed growth mechanisms, Biscarini et al [5], Zhao et al [6], Tsamouras and Palasantzas [7], and Fortin and Lu [8,9] suggest that diffusion plays a decisive role in the formation of surface morphology.…”

“…Recent experimental investigations on polymer film growth have shown quite different scaling exponents, but the surface RMS roughness w increased with the substrate temperature [5][6][7]. Despite the difference in the detailed growth mechanisms, Biscarini et al [5], Zhao et al [6], Tsamouras and Palasantzas [7], and Fortin and Lu [8,9] suggest that diffusion plays a decisive role in the formation of surface morphology. Without any other roughening mechanisms in the growth, and according to all the growth models proposed for dynamic scaling, the effect of higher substrate temperature should eventually smooth the surface, instead of increasing surface roughness.…”

Impact of Structure and Morphology on Charge Transport in Semiconducting Oligomeric Thin‐Film Devices

“…The transition in morphology was most pronounced in the range of 50-60 8C, which is in agreement with earlier findings. [9] The RMS roughness (4 4 mm 2 area) and the mean domain size obtained by AFM are listed in Table 2. Increasing T sub also results in a change of the microcrystallite shape from wedgelike at T sub = 23 8C to extended platelets for T sub !…”