Effect of annealing on the mobility and morphology of thermally activated pentacene thin film transistors
Effect of annealing on the mobility and morphology of thermally activated pentacene thin film transistors
复制标题
DOI：
10.1063/1.2193055
复制
发表时间：
2006-05-01
影响因子：
3.2
通讯作者：
Terashima, K
中科院分区：
文献类型：
--
作者：
Guo, D;Ikeda, S;Terashima, K
采用有机分子束沉积方法制备并五苯薄膜晶体管(TFT)。为了研究热退火对晶体管的形貌和载流子迁移率的影响，对TFT进行了表征。对于所有的TFT样品，迁移率与温度呈Arrhenius关系，这表明热激活的输运可以用载流子陷阱和热释放输运机制来解释。因此，为了研究退火效应，我们在退火后对数据进行了很长一段时间的测试，直到温度恢复到室温，从而筛选出热激活效应，并排除了热膨胀和应力的可能影响。结果发现，只有在低于45℃的临界温度下才能提高迁移率，而T>；50℃的退火会使迁移率比退火前降低。原子力显微镜观察和X射线衍射仪(XRD)数据表明，退火使所有样品的晶粒度减小，X射线衍射峰强度降低。将热处理温度提高到70℃时，由于有机薄膜中的范德华分子间作用力较小，导致了明显的脱附。高温退火后的迁移率下降可能归因于微结构的恶化，而迁移率的改善可能是由于靠近衬底薄膜界面的底层几层结晶度增加所致。结果还表明，在研究随温度变化的输运性质时，应区分可能的结构演化的影响。(C)2006年美国物理研究所。
Pentacene thin film transistors (TFTs) were fabricated by the organic molecular beam deposition method. The TFTs were characterized in order to study the effect of thermal annealing on the morphology and carrier mobility of the transistors. For all the TFT samples the mobility exhibited an Arrhenius relationship with temperature, indicating a thermally activated transport that could be explained by the carrier trap and thermal release transport mechanism. Therefore, in order to investigate the annealing effect, we tested the data for a significant period of time after annealing until the temperature recovered to room temperature, so that the thermal activation effect was screened and possible effects of thermal expansion and stress were also ruled out. As a result, we found that only with a temperature below a critical temperature of approximately 45 degrees C could annealing improve the mobility, while annealing with T>50 degrees C would decrease the mobility compared to the value before annealing. Atomic force microscopy observation and x-ray diffraction (XRD) data indicated that annealing caused decreased grain size and decreased XRD peak intensity for all samples. Increasing the annealing temperature to 70 degrees C caused obvious desorption because of the low van der Waals intermolecular forces in the organic film. The mobility deterioration after high temperature annealing may be ascribed to the deteriorated microstructure, while the improved mobility may result from the increased crystallinity in the bottom several layers near the substrate film interface. The results also suggested that the influence of possible structure evolution should be distinguished when investigating temperature dependent transport properties. (C) 2006 American Institute of Physics.