Quantitative evaluation of spatial scale of carrier trapping at grain boundary by GHz-microwave dielectric loss spectroscopy
Quantitative evaluation of spatial scale of carrier trapping at grain boundary by GHz-microwave dielectric loss spectroscopy
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DOI：
10.1088/1742-6596/924/1/012002
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发表时间：
2017-11
期刊：
影响因子：
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通讯作者：
Wookjin Choi;Yusuke Tsutsui;Tomoyo Miyakai;T. Sakurai;Shu Seki
中科院分区：
文献类型：
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作者：
Wookjin Choi;Yusuke Tsutsui;Tomoyo Miyakai;T. Sakurai;Shu Seki
载流子迁移率是电子导电材料的一个重要参数，传统的直流评价方法很难得到载流子迁移率的本征极限。在本研究中，我们使用基于微波的介电损耗谱(时间分辨微波电导率测量)在交流载流子局域运动模式下定量地估计了并五苯薄膜的晶内空穴迁移率。用不同的绝缘聚合物或衬底温度真空沉积并五苯层制备了金属-绝缘体-半导体器件，得到了四种不同晶粒度的并五苯层。在局部运动由并五苯晶界(晶粒-晶界)处的界面陷阱决定的条件下，观察到的空穴迁移率与晶粒度的关系被绘制成图，并用代表边界长度的抛物线函数成功地给出了很好的关联。由此估算出空穴的晶内迁移率和陷阱释放时间分别为15cm2 V−1、S−1和9.4ps。
Charge carrier mobility is an important primary parameter for the electronic conductive materials, and the intrinsic limit of the mobility has been hardly access by conventional direct-current evaluation methods. In the present study, intra-grain hole mobility of pentacene thin films was estimated quantitatively using microwave-based dielectric loss spectroscopy (time-resolved microwave conductivity measurement) in alternating current mode of charge carrier local motion. Metal-insulator-semiconductor devices were prepared with different insulating polymers or substrate temperature upon vacuum deposition of the pentacene layer, which afforded totally four different grain-size conditions of pentacene layers. Under the condition where the local motion was determined by interfacial traps at the pentacene grain boundaries (grain-grain interfaces), the observed hole mobilities were plotted against the grain sizes, giving an excellent correlation fit successfully by a parabolic function representative of the boarder length. Consequently, the intra-grain mobility and trap-release time of holes were estimated as 15 cm2 V−1 s−1 and 9.4 ps.