The Polarity Conversion And Application Of Stannous Oxide Thin Film Transistor

Display devices are already indispensable in current social life and have been integrated into people’s work and study.With the improvement of living standards,large array and cheap display devices have become necessary products in people’s life.The thin film transistor（TFT）has good switching characteristics,it is introduced into the display device as the core switching element and driving element,can improve the display device in all aspects of the property,so as to meet people’s higher and higher requirements.Therefore,it is of great significance to conduct extensive and in-depth research on thin film transistors.However,oxide film most of current research achievements is the n type conductive,in order to achieve the important breakthrough of the complementary metal oxide semiconductor technology and high-performance p-n junction device,achieve further progress in the field of transparent,flexible display,the p type and bipolar conductive oxide semiconductor thin film research is particularly important.Stannous oxide（SnO）with its excellent performance gradually into the field of vision of researchers,researchers around the world pay their close attention and extensive research on it.This paper mainly studied the polarity conversion of SnO thin film transistor from p type to bipolar type and n type,and then prepared the inverter based on SnO thin film transistor.The specific research contents are as follows:（1）Several parameters affecting the performance of p-type SnO thin film transistors were investigated in detail,including film thickness,oxygen ratio,sputtering power and annealing temperature.（2）The process conditions for the transformation of p-type SnO thin film transistor to bipolar type were studied.Bipolar SnO TFT was obtained by passivation and annealing,this is because the passivation of alumina can greatly reduce the density of defect states in the SnO band gap,so that Fermi level can move freely from the top of valence band to the bottom of conduction band under the control of gate voltage.Bipolar SnO TFT was obtained by annealing,passivation and annealing at higher temperatures with a switching ratio of over 10⁴,because annealing at higher temperature will accelerate the consumption of Sn and reduce the related defects such as Sn gap and surface defect density,so that Fermi level can move freely from the top of valence band to the bottom of conduction band.（3）The process conditions for the transformation of p type SnO thin film transistor to n type were studied.N type SnO TFT was obtained by passivation,annealing,higher temperature annealing,this is due to there are a lot of Sn and the large number of acceptor defects related in the film after passivation,annealing treatment,and with the increase of annealing temperature,acceptor defects gradually disappear,so the hole carrier concentration decreases,but n-type performance has not been much affected,so the n-type performance of the transistor is gradually higher than the p-type performance.（4）The p and n SnO TFTs are used to construct inverter,and higher gain and noise tolerance were obtained.At V_DD=70 V,the gain reached 34.90,and the noise tolerance reached 18.10 V and 22.74 V at high and low input voltage respectively.