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Spectroscopic observation of the field induced carrier doping effect in ultrathin layers of organic semiconductors

有机半导体超薄层场致载流子掺杂效应的光谱观察

基本信息

批准号：
16560028
负责人：
IKEGAMI Keiichi
金额：
$ 1.79万
依托单位：
National Institute of Advanced Industrial Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

In order to provide a basis for understanding the field-induced carrier doping (FICD) phenomenon in ultrathin organic semiconductor layers, firstly, we have adopted a theoretical approach. In this approach, a metal/insulator/semiconductor/metal four-layer model has been considered. Introduction of several physical approximations has simplified the model and allowed us to solve analytically the simultaneous derivative equation describing the model according to the Fermi distribution and the Gauss law. The behavior of the obtained solution has been examined by setting the parameters to the cases in which the insulator and semiconductor layers are made by Langmuir-Blodgett (LB) technique. This approach has shown the next two points : i) Though the FICD phenomenon becomes nonlinear, the thickness of the accumulation layer is kept much smaller than the thickness of the semiconductor layer (ds) even when both of ds and the density of states in that layer are very small ; ii) In the other cas … More es the FICD phenomenon is essentially the same as that in the inorganic devices.As an experimental approach, we have planned to apply modified infrared reflection-absorption spectroscopy (IR-RAS) techniques to metal/insulator/semiconductor/metal four-layer devices made of LB films. Two types of the modified IR-RAS technique have been prepared. The low-frequency type switches on and off the U.C. bias voltage applied to the device after each Fourier-transform (FT) scan completes so that the spectrometer records the difference between the RAS signals with and without the bias voltage. The high-frequency type applies A.C. (1-100 kHz) bias voltage to the device and inserts a phase-sensitive detector between the IR detector-signal preamplifier and the analogue-to-digital converter so that the spectrometer records the difference between the RAS signals with and without the bias voltage, too.The low-frequency type has been applied to four-layer devices with LB films of alkylTCNQ (as the semiconductor layer), LB films of fatty acid (as the insulator layer), LB films of the BO-fatty acid mixture (as one of the metal layer), and evaporated gold film (as the other metal layer) and changes in the RAS signal induced by the bias voltage have been detected. Unfortunately, however, the observed changes are not fully reversible and then we have concluded that some electrochemical effect occurs. At present, we are trying to eliminate the electrochemical effect and to observe the pure FICD effect by optimizing the sample structure, the magnitude and the frequency of the bias voltage, etc. Less

为了给理解有机半导体层中的场致载流子掺杂（FICD）现象提供基础，首先，我们采用了一种理论方法。在这种方法中，金属/绝缘体/半导体/金属四层模型已被认为是。几个物理近似的引入简化了模型，并允许我们解析地解决根据费米分布和高斯定律描述的模型的导数方程。所获得的解决方案的行为已被检查通过设置参数的情况下，其中的绝缘体和半导体层由LB技术。这种方法表明了以下两点：i）虽然FICD现象变得非线性，但即使当半导体层中的ds和态密度都很小时，积累层的厚度也保持远小于半导体层的厚度（ds）; ii）在其他情况下，尽管FICD现象变得非线性，但当半导体层中的ds和态密度都很小时，积累层的厚度保持远小于半导体层的厚度（ds）。 ...更多信息作为一种实验方法，我们计划将改进的红外反射-吸收光谱（IR-RAS）技术应用于LB膜金属/绝缘体/半导体/金属四层器件。两种类型的改进的IR-RAS技术已经准备就绪。低频型开关U.C.在每个傅里叶变换（FT）扫描完成之后施加到器件的偏置电压，使得光谱仪记录具有和不具有偏置电压的RAS信号之间的差异。高频型采用交流。（1-100 kHz）的偏置电压，并在红外探测器信号转换器和模数转换器之间插入相敏探测器，使光谱仪也能记录有和无偏置电压时RAS信号之间的差异。低频型已应用于具有烷基TCNQ LB膜（作为半导体层）的四层器件，LB膜的脂肪酸（作为绝缘体层），LB膜的BO-脂肪酸混合物（作为金属层之一），和蒸发的金膜（作为另一个金属层）和RAS信号的变化引起的偏置电压已被检测到。然而，不幸的是，观察到的变化是不完全可逆的，然后我们得出结论，发生了一些电化学效应。目前，我们正试图通过优化样品结构、偏置电压的大小和频率等来消除电化学效应，观察纯FICD效应。Less