Preparation Of Mn-Zn-Ni-（Mg）-O Thin Film Materials And Their Optical And Electrical Properties

Thermistor is a kind of material whose resistivity decreases exponentially with the increase of temperature.Because of its special electrical properties,it can be applied to various temperature measurement and control fields.In addition,it has the functions of infrared absorption,temperature compensation and surge current suppression.In this paper,metal multilayers were prepared by electron beam evaporation,and Mn based spinel thermal sensitive thin films were formed by thermal annealing.The process parameters and annealing temperature in the process of film preparation were investigated.Then,the effects of Mg doping on the structure,morphology,photoelectric and aging properties of Mn-Zn-Ni-O thin films were studied.The main contents of this paper are as follows:1.The effect of deposition rate on the physical properties of Mn-Zn-Ni-O films was studied.The experimental results show that the crystallinity and roughness of the films are higher and the concentration ratio of Mn³⁺/Mn⁴⁺is closer to 1 at lower deposition rate.At the same time,too fast deposition rate will lead to the decrease of crystalline quality,the increase of interfacial stress,and even the film falling off from the substrate surface.2.The effect of deposition period on the physical properties of Mn-Zn-Ni-O films was studied.The experimental results show that the change of deposition period has little effect on the crystallinity of the films.The growth mode of the films is island growth after four cycles.The particle size of the sample decreases with the increase of deposition period,but the roughness first decreases and then increases.When deposited for two cycles,the B value of the sample is 3579.5,the hysteresis coefficient is 0.999,the crystallinity is good and the electrical properties are excellent.3.The effect of Mg doping on the physical properties of Mn-Zn-Ni-O thin films was studied.Mg_xMn₂Zn_0.2Ni_0.8-xO₄（x=0.2,0.4,0.6,0.8）thin films were prepared by changing Mg doping content.The results show that with the increase of Mg content,the particle size decreases,the density decreases,the roughness increases and R₃₁₀ increases.The absorption peak intensity of Mn³⁺and Mn⁴⁺ions also changed with Mg doping.Among them,the B value of x=0.2 is the largest,and its aging coefficient is 12.4%.4.The effects of different heat treatment temperatures on the physical properties of Mg_0.2Mn₂Zn_0.2Ni_0.6O₄ thin films were studied.The results show that the phase structures of Mn₂O₃ and Mg Mn₂O₄ appear at higher annealing temperature.The samples annealed at750℃have higher crystallinity and B value;From 650℃to 850℃,the distribution of metal cations has little change.The aging characteristic test results show that the aging coefficient of the samples annealed at 850℃is 16.3%,which indicates that Mg and Zn can stabilize the distribution of Mn³⁺and Mn⁴⁺metal cations.