Fabrication And Researching Of New Type Transistors

Organic thin-film transistors(OTFTs) have attracted enormous attentions in the last decades. They are extensively used in the field of OLEDs, sensors and RFID.But many aspects which need to be improved have been deeply researched such as mobility, Ion/ Ioff ratio and project usage.This thesis simply introduces the researching progress and highlights of OTFTs. And this thesis also introduces the fundamental structures, working mechanism and important parameters of OTFTs. Besides these, this thesis illustrates the process of fabricaton of OTFTs including instruments and the methods of fabricaton and testing.Aiming to solve the low mobility and high VT of tranditional OTFT caused by contact barrier, this thesis provides a method to improve the character of OTFT by modifying the electrodes. We insert an enough thin Li F layer between electrodes and active layer and get the mobility and VT well improved. When the thickness of Li F layer is from 0-1.2nm, the mobility ascends and VT descends. But when the thickness of Li F layer is larger than 1.2nm, the character of OTFT decreased.This thesis emphasizes on a kind of OHJTs. Aiming to solve the low Ion/Ioff ratio of tranditional OHJTs, this kind of OHJTs highly increase the quatity of free charges in the channel by heterojunction effect and thus enhance the performance. And we research that when the thickness of the semiconductor layer upon Si O2 is 1nm, the off state current is well controlled. So this kind of OHJTs could enhance mobility and Ion/Ioff ratio simultaneously.And this thesis also detects the reason of why the thickness of Pentacene could affect the performance of OHJTs by the theory of heterojuncyion and the detecting results of AFM. We illustrate the relationship among the thickness of the semiconductor layer upon Si O2, the surface of the film and the crystallinity of the film. And we conclude that when the thickness of Pentacene is 1nm, the thickness of the semiconductor layer upon Si O2, the surface of the film and the crystallinity of the film achieve the best balance and so the OHJT achieve the best performance, too.