Photoelectrical Properties Of CuO-Ga₂O₃ Pseudobinary Systerm Compounds

CuO-Ga2O3 pseudo-binary system contains two compounds,which are CuGaO2 and CuGa2O4.Cu ions are positive monovalent in CuGaO2,Cu ions are positive divalent in CuGa2O4.CuGaO2 is a transparent conductive oxide semiconductor,which hava a optical band gap about 3.1 eV.CuGaO2 has a large transmittance within the visible wavelength range,usually within the range.from 70%.to 80%.CuGaO2 has a high reflectivity in the range of infrared wavelength and obvious cutoff characteristics in the ultraviolet wavelength region.So,CuGaO2 have great application potential in the fields of transparent conductive electrode,light-emitting diode and solar cell.CuGa2O4 is a metal oxide semiconductor.It has a cubic spinel structure which is similar to the structure of ?-Ga2O3.And the difference of lattice constant of CuGa2O4 and ?-Ga2O3 is much small.CuGa2O4 is also a wide band gap semiconductor.The band gap of CuGa2O4 is close to that of Ga2O3.Besides,CuGa2O4 has good thermal stability.Therefore,CuGa2O4 has the potential to replace the position of ?-Ga2O3 in practical applications fields and great potential in the fields of optoelectronic devices.Based on the outstanding application potential of the two kinds of materials of CuO-Ga2O3 pseudo system and study related with optical properties of materials about Ga2O3,this paper systematically studies the physical properties of two kinds of material CuO-Ga2O3 pseudo system.The main achievements are as follows:1.Different proportions of CuO and ?-Ga2O3 powders(which can be expressed by chemical CuxCu1-xOy)were sintered in air at different temperatures,and the sintered powder products under such experimental conditions were studied.The experimental results show that all sintered products of x=0.05,0.1,0.15,0.2,0.25,0.3 and 0.33 have only two phases at the sintering temperature of 1000?,CuGa2O4 and ?-Ga2O3.In other words,no matter what the ratio of CuO to ?-Ga2O3 is,CuO only reacts with an equal proportion of ?-Ga2O3 to produce CuCu2O4.This shows that the CuGaO2 can not be obtained by the solid-state reaction under conditions that the reaction atmosphere is air and the experimental temperature is at 1000?.Then we sintered the mixture of CuO and?-Ga2O3 in a ratio of 1:1 in air at the temperature of 1000?.The results show that although the ratio of CuO to ?-Ga2O3 is 1:1,there is still a small amount of ?-Ga2O3 at 800?.That is,the reaction is not complete.However,when the temperature of sintering is 1000?,CuO and ?-Ga2O3 completely react,and only CuCu2O4 is contained in the sintered product.That is,equal proportions of CuO and ?-Ga2O3 react in the air to form pure CuGa2O4 at a temperature of 1000?.The reaction products of the same proportion of the powder samples sintered at the same temperature in the nitrogen atmosphere are the same as that in the air.They are all CuGa2O4 and Ga2O3,which means that CuGaO2 can not be obtained at the temperature of 1000 ? in the atmosphere of nitrogen.2.At the temperature of 1000?,we studied the sintered products of different proportions of CuO and ?-Ga2O3 powders in air atmosphere.The results showed that only CuCu2O4 and the residual Ga2O3 were found in the sintered products of all the samples,and the doping phase of Cu and Ga2O3 did not appear.Even in the sintered products of x=0.05 samples,Cu was not able to adulterate into the lattice of Ga2O3,which means that the solid solubility of Cu in Ga2O3 is very low,and it is difficult to adulterate into Ga2O3.3.The effect of temperature on the crystal phase,crystal quality and optical band gap of CuGa2O4 thin film was studied by using pulsed laser deposition(PLD)technology with pure CuGa2O4 sintered in the air with equal proportion of CuO and ?-Ga2O3 powders as the target.The results show that the CuGa2O4 film grown on the substrate of ?-Al2O3 has preferred orientation along the(111)crystal plane and spinel structure,and the crystalline quality of the films improves with the increase of temperature.When the temperature is at 750?,the crystal quality of the film is the best.The optical band gap of the film decreases with the improvement of the crystal quality,and the band gap of the film is also the smallest when the crystal quality is best at 750?,which is 4.35 eV.