界面修饰对氧化锌基薄膜晶体管性能的影响
摘要
本论文的主要内容为研究以氧化锌薄膜为有源层,制备氧化锌薄膜晶体管(ZnO-TFT),分别从氧化锌薄膜的厚度,利用不同材料进行界面修饰,以及有机无机复合等角度对氧化锌薄膜晶体管的电学性能进行了研究。
首先,利用磁控溅射的方法,使用纯度为99.99%锌作为靶材,通过控制不同的氩气与氧气的比例以及调节溅射功率,得出了制备氧化锌薄膜的最佳成膜条件。通过研究发现,在Ar：O2为30sccm:25sccm,溅射功率为300W,400℃退火10min时,通过XRD和AFM测试表明在此条件下成膜质量最佳。
其次,在上述最佳的成膜条件下,利用磁控溅射的方法,通过控制溅射的时间,分别在600s、800s、1000s、1200s的溅射时间里,得到了45nm、60nm、75nm、95nm四个不同厚度的氧化锌薄膜层,制备出器件,通过测试它们的电学性质,得到在600s的溅射时间时,氧化锌薄膜晶体管的性质较好,迁移率为：0.789cm2/V·s,随着溅射时间的增加,从800s到1200s的器件的迁移率分别是：0.271cm2/V·s、0.271cm2/V·s、0.285cm2/V·s,通过XRD和AFM表征发现在45nm厚度下,薄膜同时沿垂直于衬底和平行于衬底方向生长,沿载流子传输方向的品界密度低,薄膜表面形貌最佳,成膜质量最好,因此得到的晶体管的性能相对最好。
第三,利用氟化锂对有源层和铝电极之间的界面进行了修饰,发现通过氟化锂的界面修饰,器件的迁移率都有所上升,在有源层厚度为45nm时,器件的迁移率达到了0.920cm2/V·s,从800s到1200s的器件的迁移率分别是0.278 cm2/V·s、0.319cm2/V·s、0.304 cm2/V·s。随后,利用氧化钼对器件有源层和铝电极之间的界面进行了修饰,发现通过氧化钼的界面修饰,器件的迁移率都有所下降,在有源层厚度为45nm时,器件的迁移率降到了0.531cm2/V·s,厚度为95nm的器件的迁移率是0.263 cm2/V·s。
第四,研究了不同厚度并五苯薄膜的薄膜质量,利用热蒸发,制备了5,10,15,20,30,40,50,60nm八个厚度的并五苯薄膜,通过XRD测试得出所制备薄膜在10nm至40nm厚度时成膜质量较好。
第五,将氧化锌和并五苯两种不同的有源层复合制成氧化锌／并五苯薄膜晶体管(ZnO/Pentacene-TFT),利用在氧化锌薄膜上热蒸发一层并五苯薄膜制备出了ZnO/Pentacene-TFT,通过实验发现在不添加界面修饰材料PhTMs的情况下,器件的迁移率高于有PhTMs修饰的器件,迁移率为0.552cm2/V.s。
最后,制备了并五苯厚度为10nm、20nm、30nm、40nm,氧化锌厚度为45nm的四个器件,并通过测量其电学性质发现在氧化锌薄膜厚度为45nm,并五苯薄膜厚度为1Onm时,器件的迁移率最高,为0.552cm2/V.s。
The main content of this thesis is research the active layer of ZnO thin film transistor (ZnO-TFT) prepared by zinc oxide thin films. We research zinc oxide thin film transistor's electrical properties from the point of thickness of ZnO thin films, interfacial modification of the use of different materials, and organic-inorganic compound.
First, we use the method of magnetron sputtering, we obtained the best film-forming conditions of preparation the ZnO thin films with purity of 99.99% zinc as a target, by controlling the different ratio of argon and oxygen, and adjust the sputtering power. Through XRD and AFM tests, we found the best film-forming conditions are Ar:O2 is 30sccm:25sccm, sputtering power of 300W,400℃annealing 10min.
Second, we use the method of magnetron sputtering, get 45nm,60nm,75nm,95nm four different thickness of ZnO thin film layer by controlling the sputtering time at the sputtering time of 600s,800s,1000s,1200s. we found that in the 600s sputtering time, zinc oxide thin film transistors has best migration rate:0.789cm2/V·s, with the sputtering time increases from 800s to 1200s, migration rate of devices are: 0.271cm2/V·s,0.271 cm2/V·s,0.285cm2/V·s. Characterized by XRD and AFM found that in 45nm thickness film grows at the direction of both perpendicular and parallel to the substrate. grain boundary density is low along the direction of carrier transport. The film has best surface roughness and best film quality, So the devices has best performance at this film thickness.
Third, the use of lithium fluoride modified the interface between the aluminum electrode and the active layer. Through the modified of the interface, migration rate of all devices are on the rise. When the active layer thickness is 45nm, the device The migration rate reached 0.920cm2/V·s, the device from the 800s to the 1200s the migration rate was 0.278cm2/V·s,0.319cm2/V·s,0.304cm2/V·s. Subsequently, the use of molybdenum oxide modified the interface between the aluminum electrode and the active layer. Through the modified of the interface, migration rate of all devices are decreased. When the active layer thickness is 45nm, the device The migration rate is 0.531cm2/V·s, the thickness of 95nm devices migration rate is 0.263cm2/V·s.
Fourth, research the quality of pentacene thin films with different thickness, which is prepared by thermal evaporation, thickness of pentacene film is 5,10,15,20,30,40,50,60nm, obtained Preparation of thin film thickness of 10nm to 40nm film has better quality testd by XRD.
Fifth, use the two different active layer-zinc oxide and pentacene composite made of zinc oxide/pentacene thin-film transistor(ZnO/Pentacene-TFT). Using the thermal evaporation prepared pentacene thin films. Then made the ZnO/Pentacene-TFT. The experiment found that migration of device without adding interface PhTMs cases, higher than the migration of the device has PhTMs, migration rate 0.552cm2/V·s.
Finally, we fabricated ZnO/Pentacene-TFT with the thickness of pentacene range from 10nm to 40nm, and the thickness of ZnO of 45nm.then measuring the electrical properties. The result suggest that when the zinc oxide film thickness in the 45nm, and lOnm thick pentacene film, The device migration rate was the highest 0.552cm2/V·s.
首先,利用磁控溅射的方法,使用纯度为99.99%锌作为靶材,通过控制不同的氩气与氧气的比例以及调节溅射功率,得出了制备氧化锌薄膜的最佳成膜条件。通过研究发现,在Ar：O2为30sccm:25sccm,溅射功率为300W,400℃退火10min时,通过XRD和AFM测试表明在此条件下成膜质量最佳。
其次,在上述最佳的成膜条件下,利用磁控溅射的方法,通过控制溅射的时间,分别在600s、800s、1000s、1200s的溅射时间里,得到了45nm、60nm、75nm、95nm四个不同厚度的氧化锌薄膜层,制备出器件,通过测试它们的电学性质,得到在600s的溅射时间时,氧化锌薄膜晶体管的性质较好,迁移率为：0.789cm2/V·s,随着溅射时间的增加,从800s到1200s的器件的迁移率分别是：0.271cm2/V·s、0.271cm2/V·s、0.285cm2/V·s,通过XRD和AFM表征发现在45nm厚度下,薄膜同时沿垂直于衬底和平行于衬底方向生长,沿载流子传输方向的品界密度低,薄膜表面形貌最佳,成膜质量最好,因此得到的晶体管的性能相对最好。
第三,利用氟化锂对有源层和铝电极之间的界面进行了修饰,发现通过氟化锂的界面修饰,器件的迁移率都有所上升,在有源层厚度为45nm时,器件的迁移率达到了0.920cm2/V·s,从800s到1200s的器件的迁移率分别是0.278 cm2/V·s、0.319cm2/V·s、0.304 cm2/V·s。随后,利用氧化钼对器件有源层和铝电极之间的界面进行了修饰,发现通过氧化钼的界面修饰,器件的迁移率都有所下降,在有源层厚度为45nm时,器件的迁移率降到了0.531cm2/V·s,厚度为95nm的器件的迁移率是0.263 cm2/V·s。
第四,研究了不同厚度并五苯薄膜的薄膜质量,利用热蒸发,制备了5,10,15,20,30,40,50,60nm八个厚度的并五苯薄膜,通过XRD测试得出所制备薄膜在10nm至40nm厚度时成膜质量较好。
第五,将氧化锌和并五苯两种不同的有源层复合制成氧化锌／并五苯薄膜晶体管(ZnO/Pentacene-TFT),利用在氧化锌薄膜上热蒸发一层并五苯薄膜制备出了ZnO/Pentacene-TFT,通过实验发现在不添加界面修饰材料PhTMs的情况下,器件的迁移率高于有PhTMs修饰的器件,迁移率为0.552cm2/V.s。
最后,制备了并五苯厚度为10nm、20nm、30nm、40nm,氧化锌厚度为45nm的四个器件,并通过测量其电学性质发现在氧化锌薄膜厚度为45nm,并五苯薄膜厚度为1Onm时,器件的迁移率最高,为0.552cm2/V.s。
The main content of this thesis is research the active layer of ZnO thin film transistor (ZnO-TFT) prepared by zinc oxide thin films. We research zinc oxide thin film transistor's electrical properties from the point of thickness of ZnO thin films, interfacial modification of the use of different materials, and organic-inorganic compound.
First, we use the method of magnetron sputtering, we obtained the best film-forming conditions of preparation the ZnO thin films with purity of 99.99% zinc as a target, by controlling the different ratio of argon and oxygen, and adjust the sputtering power. Through XRD and AFM tests, we found the best film-forming conditions are Ar:O2 is 30sccm:25sccm, sputtering power of 300W,400℃annealing 10min.
Second, we use the method of magnetron sputtering, get 45nm,60nm,75nm,95nm four different thickness of ZnO thin film layer by controlling the sputtering time at the sputtering time of 600s,800s,1000s,1200s. we found that in the 600s sputtering time, zinc oxide thin film transistors has best migration rate:0.789cm2/V·s, with the sputtering time increases from 800s to 1200s, migration rate of devices are: 0.271cm2/V·s,0.271 cm2/V·s,0.285cm2/V·s. Characterized by XRD and AFM found that in 45nm thickness film grows at the direction of both perpendicular and parallel to the substrate. grain boundary density is low along the direction of carrier transport. The film has best surface roughness and best film quality, So the devices has best performance at this film thickness.
Third, the use of lithium fluoride modified the interface between the aluminum electrode and the active layer. Through the modified of the interface, migration rate of all devices are on the rise. When the active layer thickness is 45nm, the device The migration rate reached 0.920cm2/V·s, the device from the 800s to the 1200s the migration rate was 0.278cm2/V·s,0.319cm2/V·s,0.304cm2/V·s. Subsequently, the use of molybdenum oxide modified the interface between the aluminum electrode and the active layer. Through the modified of the interface, migration rate of all devices are decreased. When the active layer thickness is 45nm, the device The migration rate is 0.531cm2/V·s, the thickness of 95nm devices migration rate is 0.263cm2/V·s.
Fourth, research the quality of pentacene thin films with different thickness, which is prepared by thermal evaporation, thickness of pentacene film is 5,10,15,20,30,40,50,60nm, obtained Preparation of thin film thickness of 10nm to 40nm film has better quality testd by XRD.
Fifth, use the two different active layer-zinc oxide and pentacene composite made of zinc oxide/pentacene thin-film transistor(ZnO/Pentacene-TFT). Using the thermal evaporation prepared pentacene thin films. Then made the ZnO/Pentacene-TFT. The experiment found that migration of device without adding interface PhTMs cases, higher than the migration of the device has PhTMs, migration rate 0.552cm2/V·s.
Finally, we fabricated ZnO/Pentacene-TFT with the thickness of pentacene range from 10nm to 40nm, and the thickness of ZnO of 45nm.then measuring the electrical properties. The result suggest that when the zinc oxide film thickness in the 45nm, and lOnm thick pentacene film, The device migration rate was the highest 0.552cm2/V·s.
引文
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[2]W.Shockley.A Unipolar"Field-Effect"Transistor Proc.IEEEE 40,1365(1952)
[3]P.K.Weimer.The TFT-A New Thin Film Transistor.Proc.IEEE 50,1462(1962).
[4]Y.Segawa,A.Ohtomo,M.Kawasaki,H.Koinuma.Growth of ZnO Thin Film by Laser MBE:Lasing of Exciton at Room Temperature.physica status solidi.Volume 202,Issue 2,pages 669-672,August 1997.
[5]R.L.Hoffman,B.J.Norris,J.F.Wager.ZnO-based transparent thin-film transistors.APPLIED PHYSICS LETTERS.2003.82,5.733-735
[6]wagner S,Gleskova H,Cheng 1 C,et al.Thin Solid Films.2003,430.15-19.
[7]Kim B D,Jung H,Kim G B,et al. Microelectronic Journal.2003,34.767-771.
[8]Yasuo C,Ashraful I,Yuki W,et al. Japanese Journal of Applied Physics,2006,45(60).638-640.
[9]Angelis F D,Toccoli T.Pallaoro A,et al. Synthetic Metals.2004,146.291-295.
[10]Satoshi Masuda,Ken Kitamura,Yoshihiro Okumura,and Shigehiro Miyatake.Transparent thin film transistors using ZnO as an active channel layer and their electrical properties.JOURNAL OF APPLIED PHYSICS.2003.93(3).1624-1630
[11]M.M.De Souza,S.Jejurikar,K.P.Adhi.Impact of aluminum nitride as an insulator on the performance of zinc oxide thin film transistors.APPLIED PHYSICS LETTERS.2008.92,093509.2-3
[12]唐伟忠.薄膜材料制备原理,技术及应用.北京.冶金工业出版社.2003.162-197.
[13]S.M.Tadayyon,H.M.Grandin,K.Griffiths,et al.Organic Electronics,2004,5:157.166.
[14]Yunhua Xu,Jtmbiao Peng,Jiaxing Jiang,et al.Appl.Phys.Lett.2005,87:193502(1-3).
[15]K.Book,H.Bassler,A.Eischner,S.Kirehmeyer.Organic Electronics,2003,4.227-232.
[16]董建新,方亮,张淑芳.ZnO上欧姆接触的研究进展.2007,38.907-912.
[17]Pearton S J,Norton D P,Ip K,et al.Recent progress in processing and properties of ZnO.Supperlattices and Micro structures,2003,34(12).3-32.
[18]Shimura Y,Nomura K H.Yanagi H,et al.Specific contact resistances between amorphous oxide semiconductor InGaZnO and metallic electro des.Thin Solid Films.2008,516(17).5899-5902.
[19]ItoM,MiyazakiC,IshizakiM,et al. Application of amorphous oxide TFT to electrophoretic display.Non-crystSolids,2008,354(19225).2777-2782.
[20]Ferber J,Luther J.Phys Chem B,2001,105.4895-4903.
[21]Hart J N.Menzies D.Cheng Yibing.et al.C R Chimie.2006,9.622-626.
[22]Nazeeruddin M K,Kay A,Gratzel M.J Am Chem Soc.1993,115(14).6382-6390.
[23]Wong H,Iwai H.On the scaling is sues and high-kreplacement of ultrathin gate dielectrics for nano scale MOS transistors.Microelec.Eng.2006,83(10).1867-1904.
[24]Wilk G D,Wallace R M,Anthony J M.High-k gate dielectrics:current status and materials properties consideration.J.Appl Phys.2001,89(10).5243-5273.
[25]Hung L S,Tang C W,Mason M G.Appl Phys Lett.1997,70(2).152-154.
[26]Brabec C J,Shaheen S E,Winder C,et al.Appl Phys Lett,2002,80(7).1288-1290.
[27]Brown T M,Friend R H,Millard I S,et al.Appl Phys Lett,2001,79(2).174-176.
[28]Parker I D.Carrier tunneling and devicee characteristics in Polymer light-emitting diodes.APPI Phys.1994,75(3).1656-1666.
[29]Jabbour G E,Kawabe Y.Shaheen S E,et al.Appl Phys Lett,1997,71 (13).1762-1764.
[30]Schlaf R,Parkinson B A,Lee PA,et al.Appl Phys.1998,84(12).6729-6736
[31]H,Sirringhaus,N,Tessler,and R.H.Friend.Field-effect integrated optoelectronic devices based on conjugated polymers.Science.1998,280.1741-1743
[32]H.Klauk,D.J.Gundlach,J.A.Nichols,T.N.Jackson.Pentacene orgnaic thin-film transistors for circuit and display applications.IEEE Trans Elect Dev 46.1999.1258-1263.
[33]C.D.Dimitrakopoulos,A.R.Brown,A.Pomp.Molecular-beam-deposited thin films of pentacene for organic field-effect transistor applications.J Appl Phys 80.1996.2501-2508.
[34]G.Horowitz,D.Fichou,X.Z.Peng,F.Garnier.Thon-film transistors based on alpha-conjugated oligomers.Syn Met 41.1991.1127-1130
[35]J.Laquindanum,H.E.Katz,A.J.Lovinger,A.Dodabalapur.Morphological origin of high mobility in pentacene thin-film transistors.Chem Mater 8.1996.2542-2544
[36]Josef W.Spalenka.Molecular control of pentacene/ZnO photoinduced charge transfer.Appl Phy Lett 98,103303(2011)
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