Measurement Theory,Technique And Applications Of The Optical And Electrical Properties Of Organic Semiconductor Film

Organic molecular thin film devices are an important branch of the fields of new generation semiconductors.Since the growth mode of organic molecular thin films is different from traditional silicon-based materials,its growth mechanism,preparation process and performance analysis are in an urgent demand of further study.Based on the study of physical mechanisms of the formation and changes of the spectrum in the deposition and growth process of organic molecular thin films,this paper builds a theoretical model for multiphase differential reflectance spectroscopy(DRS)measurements,and designs a multi-functional photoelectric device suitable for the research of organic semiconductor thin film devices.In this combined measuring instrument system,the measurement principle and impact factors are studied,in which two types of organic small molecules,the typical high-mobility rod-shaped organic molecule pentacene and the typical luminescent perylene derivative disc-shaped organic molecule Me-PTCDI,are used as examples.The main contents of this paper include:1.The mechanism of DRS in the process of organic semiconductors from monomer molecules to aggregated molecules and thin film growth is analyzed.In order to characterize the multilayer structure of organic thin film devices,a polyphase model based on the Fresnel formula was established for DRS measurement.The optical characteristic matrix simplification algorithm was introduced,and the analysis method of thin film growth based on the spectral fitting was proposed.The algorithm form,applicable conditions and influencing factors of fitting were explained.An electrical measurement method based on the principle of organic field effect transistor was constructed,the measurements and performance of which are described correspondingly.2.A wide-band,real-time and offline micro-area DRS measurement system was built in situ to fulfill the need of high signal-to-noise ratio of this system.The source of the system noise was analyzed and verified,and a simple and effective noise suppression scheme was proposed.An electrical measurement system suitable for insitu and real-time detections of organic thin-film devices was built,in which the hardware construction,software writing and connection in a high vacuum system were realized.3.A silicon-based organic field-effect electrical device was specially designed and made for the research of this paper.The combined real-time and online photoelectric measurements of the growth of the pentacene semiconductor layer for the device sample was carried out.Based on the theoretical calculations and measurements of the DRS multiphase model,the molecular orientation,growth mode,crystal phase transition,film thickness and other changes of the pentacene layer during the growth process were studied along with the analysis of characteristic peaks and spectral fitting.By obtaining the working curves of the devices in real-time measurements,the electrical characteristics of the pentacene field effect tube,including the conduction characteristics,the saturation characteristics and the contact characteristics of the metal electrodes are obtained and described in this part.4.Molecular Me-PTCDI thin films with different layer thicknesses were prepared on the surface of the two-dimensional material h-BN substrate.Through the offline micro-area DRS spectroscopy measurements,the changes of molecular aggregation morphology and electronic properties of Me-PTCDI with the layer thickness were studied in this part.