Investigation On Preparation And Electrical Transport Properties Of In₂se₃ Nanowire Devices

In₂Se₃ nanowires have strong anisotropy,good electrical properties and theoretically high carrier mobility.On the other hand,for semiconductor devices,property of contact between semiconductors and electrode metals is particularly important,which directly affects performance of the devices.Up to now,there are few researches on the contact properties between the nanowires and electrode metals in In₂Se₃ nanowire devices.In this work,the main research object is In₂Se₃ nanowires.After the growth of single crystal In₂Se₃ nanowires,the preparation methods of In₂Se₃ nanowire devices which has ohmic contact with the electrode metal were studied.Furthermore,the contact properties between In₂Se₃ nanowires and metal were investigated.First,In₂Se₃ nanowires were grown by vaporliquidsolid(VLS)method in a tubular furnace.The results show that the as grown nanowires have?-2H phase crystal structure and good single crystal structure,and blongs to hexagonal system,lattice constant:a=b=4.0?and c=19.2?.?=?=90?,?=120?.The diameter of nanowires ranges from 50 nm to 300nm,and the length can reach hundreds of microns.Then,single In₂S₃ nanowire devices were successfully fabricated with electron beam lithography.The contact resistance between In₂S₃nanowires and metal electrodes and the performance of In₂Se₃ nanowire field effect transistor were studied.The problem of ohmic contact between In₂Se₃ nanowires and metal electrode is solved.Nanowire devices were annealed at low temperature.In the prepared devices,the In₂Se₃nanowires directly form ohmic contact with the Ag electrode.In this method,Ag/Ti/Ag sandwich structure electrode is used to replace the traditional Ti/Ag two layer structure electrode.It is solved the problems that selenium escaping into vacuum and Ag atoms diffusing into nanowires.This method does not require annealing at high temperature for long time.It is only need to anneal at 150?C for 5 to 15 minutes using a heating plate,and good ohmic contact was formed between In₂Se₃ nanowires and Ag electrode.The electrode preparation method proposed in this paper not only can greatly improve the success rate of In₂Se₃ nanowire devices,but also provide a solution for other kinds of nanowire devices.By utilizing In₂Se₃ nanowire devices with ohmic contact,contact resistance between the In₂Se₃ nanowire and Ag electrode was measured.The traditional method of measuring contact resistance is improved.The contact resistance between the semiconductor nanowires and the metal electrode is more accurately extracted by equations,and the method is universal.The contact resistance of single contact is found to be 10⁴??10³?.The large variation range indicates that the contact resistance of different metal electrodes in the same nanowire is different.The transmission line model was used to analyze the contact resistivity and transmission length between metal and semiconductor.The contact resistivity is 10^-5?10^-6?·cm² and the transmission length is 1?5?m.Higher contact resistance and longer transmission length mean that there is interlayer resistance between In₂Se₃ nanowires and electrode metal.Single nanowire field effect transistors(FET)were fabricated using single crystal In₂Se₃nanowires.It is found that the resistance of the as prepared In₂Se₃ nanowire transistor is much lower than that reported previously.The transfer characteristic of the In₂Se₃ nanowire FET between voltage-30 V-30 V and transfer characteristic between voltage 0-2.7 V were measured.The carrier mobility of In₂Se₃ nanowire was calculated to be about 0.21 cm²V^-1·s^-1.