Study On The Fabrication And Properties Of Metal/SiO_x Memristive Thin Films

Silicon based memristive materials have attracted much attention due to its potential applications not only in electrical storage devives but also in optoelectronic modulators.Memristors based on amorphous silicon?a-Si?have shown its application prospects in optoelectronic field due to its compatibility with complementary metal oxide semiconductor?CMOS?technology.It is shown that amorphous silicon oxide?a-SiO_x?has been widely applied in micro-electronics.In this thesis,a-SiO_x,a-SiO_x:Ag and a-SiO_x:Cu thin films are fabricated by co-sputtering,and their microstructural and optoelectronic properties are investigated.And the resistance switching behavior of the memristor based on a-SiO_x has been studied for the first time.All of these work are aimed at seeking an application of a-SiO_x based memristor used for optical readout.The main results are as follows:?1?The a-SiO_x thin films were deposited by a radio frequency magnetron aputtering?RF-PVD?system.The influence of oxygen content on the microstructure and the optical properties of the testing films have been studied.It is found that a-SiO_x thin films are of amorphous network structure.With the increase of oxygen content,the number of Si-O-Si bonds is increased.The transmissivity and optical gap of a-SiO_x thin films are increased while the refractive index is decreased with the increase of oxygen content.?2?The a-SiO_x thin films doped with silver?Ag?or with copper?Cu?were also deposited by RF-PVD system.The influence of Ag or Cu concentration on the microstructure and optoelectronic properties of the testing films,named as a-SiO_x:Ag or a-SiO_x:Cu,have also been studied.It is found that both a-SiO_x:Ag and a-SiO_x:Cu thin films present amorphous network structure.In these two films,Ag atoms form nanocrystals distributing uniformly in a-SiO_x:Ag thin films,while Cu atoms form compounds with Si atoms?Cu₃Si?distributing in a-Si O_x:Cu thin films.With the increase of Ag or Cu concentration,the extinction coefficient and refractive index of the two thin films are increased but the transmissivities of the two films are decreased;and the resistivities of both thin films are decreased with the increase of Ag or Cu concentration.The results indicate that a-SiO_x:Ag and a-SiO_x:Cu thin films have excellent potential applications in memristive optical switches.?3?Two prototype memristors of Ag/a-Si/ITO and Ag/a-SiO_x/ITO were successfully fabricated and the resistance switching performance of these memristors have been studied.It is found that the typical resistance switching behavior of both Ag/a-Si/ITO and Ag/a-SiO_x/ITO are observed with a good constancy.Ag/a-SiO_x/ITO memristor shows a good repeatability?>100?and a high“on/off”ratio?10²?under certain parameter conditions such as the compliance current is set at 100?A,the diameter of Ag electrode is about 200?m and the thickness of a-SiO_x films is around100nm.The resistance switching performance of these two memristor are obviously influenced by the quality of memristive thin films and the fabrication processes of the memristor,and are closely related to the diameter of Ag electrode,the compliance current and the thickness of memristive layer.