Preparation And Characterization Of The P-type Metal Oxide CuAlO₂ Thin Film Transistor

In the past few decades,the metal oxide simeconductor thin-film transistors?TFTs?have been extensively investigated for the next generation active matrix liquid crystal displays,organic light emitting diode displays,and other emerging applications electronic circuits due to their excellent electrical properties and outstanding optical transparency.However,most high-performance oxide thin film transistors are made of n-type materials,such as ZnO-TFT,SnO₂-TFT,In₂O₃-TFT,InGaO-TFT,and IGZO-TFT.Due to the lack of p-type oxide semiconductor materials and the difficulty in growing high quality thin films,only little research has been conducted on p-type oxide TFTs,which greatly limits the fabrication of complementary metal oxide semiconductor?CMOS?circuits.Based up the theory of"the chemical modulation of the valence band",it was found that the delafossite CuMO₂?M=Al,Ga or Cr?material has p-type conductivity properties.And CuAlO₂ have attracted a lot of research since 1997contribute to the special properties of electrical,optical,thermoelectric and photocatalytic.Although CuAlO₂ films has received increasing attention,there are only a few reports focusing on p-type TFT using CuAlO₂ films as active layer.Therefore,it is very necessary to study the CuAlO₂-TFT film.In this paper,CuAlO₂ thin films were prepared by sol-gel method and RF magnetron sputtering method respectively.The influence of drying temperature,annealing temperature and thickness on the structural of CuAlO₂ thin films were investigated in detail.?1?The CuAlO₂ thin films were deposited on SiO₂/Si or quartz glass substrates by Sol-gel technique.Through a series of experiments,it was found that CuAlO₂ thin films dried at 350°C and 400°C are conducive to the crystallization of CuAlO₂.And the CuAlO₂ annealed at 1000°C under nitrogen atmosphere has higher visible light transmittance,wider bandgap?Eg=3.7 eV?,larger grain size,and smooth surface.?2?Bottom-gate CuAlO₂ thin film transistor were fabricated by Sol-gel technique.The influence of drying temperature,annealing temperature and thickness on the structural of CuAlO₂ thin films transistors were investigated in detail.These results show that thin-film transistor by using a 40nm thickness,drying at350°C and annealing at 1000°C the CuAlO₂ thin film as active layer has a optimized performance??3?Finally,the CuAlO₂ thin films were deposited on SiO₂/Si substrates by RF magnetron sputting technique.Through a series of experiments,it was found that the film had high crystal guality and grain fabulous when the temperature was room temperature,the power was 38W,the ratio of O₂:Ar=5:50 and the pressure was 2Pa.These results show that the CuAlO₂ thin film deposited under these conditions has optimized thin film properties,ie,higher visible light transmittance,wider bandgap,larger grain size and flatness.Then CuAlO₂ thin films were deposited on SiO₂/Si substrates by sputting technique using bottom-gate top-contact configuration with bottom gate.These results show that the electrical properties of TFTs are depended on the annealing temperature.With the incresse of the annealing temperature,the performance of the device increase.The TFT fabricated by the CuAlO₂ thin film annealed at 900°C as active layer has a optimized performance?...