Preparation And Characterization Of Zn3N2 Thin Films Synthesized By MOCVD

In recent years,nitride semiconductors have been recognized as one of the most promising class of materials for optical devices or high-speed and high-power electronic devices due to their characteristics of wide band gap,high electron saturation velocity,and high breakdown voltage[1].As the representative of the group-?-nitride materials,GaN has been widely investigated and applied[2].As a?-? nitride material,Zinc nitride films are promising significant semiconductor materials for optoelectronic devices and solar cells due to the high mobility and good electrical conductivity of zinc nitride films at room temperature.However,the preparation and optoelectronic properties of the Zn3N2 thin films have not been fully researched.Zn3N2 powder was first synthesized by Juza and Hahn in 1940[3].Until now,we can obtain Zn3N2 films by RF-magnetron sputtering[6,7],PLD[4,5],MBE[8],and an electrochemical process.Due to different growth technique and conditions,zinc nitride band gap values varied from 1.0leV to 3.4eV[9-14].The change of the optical band gap may be caused by the unintentionally doped oxygen impurity in the film.The significant change in band-gap energy for Zn3N2 extends application range in the field of optoelectronic devices.Metal organic chemical vapor deposition(MOCVD)is useful technique for large-area uniform thin films of compound semiconductors in electronic industry.Therefore,the thin films deposited by MOCVD can be beneficial for application of Zn3N2 in electronic industry.In this investigation,we used metal organic chemical vapor deposition method to prepare Zn3N2 thin films.The influence of growth conditions,such as substrate temperature,reaction pressure,II-V ratio,and annealing temperature on the structural,optical and electrical properties of the zinc nitride thin films was studied.the resistive random access memory of Zn3N2 thin films was studied.The research work and results are as follows:Zn3N2 films were prepared on quartz substrates(20mm×20mm)by metal-organic(MO)CVD.Diethylzinc was used as the zinc source and the high-purity NH3(99.9999%)was used as nitrogen source and high purity N2(99.9999%)as the carrier gas.Zn3N2 films were grown at temperature of 300-700?.There was no Zn3N2 deposition at growth temperatures below 300 ? and higher than 600 ?.With the increase of substrate temperature,the growth rates increased.When the temperatures up to 550?,the pre-reaction increased and the growth rate of the film decreased.When the substrate temperature was in the range 400-450? three dimensional growths appeared on the surface of the films.The reaction chamber pressure was varied from 10 torr to 70 torr.At the relatively low reaction chamber pressure,the precursor of the Zn3N2 film is difficult to reach the substrate and form the film.Therefore,the crystallinity of the film is poor.However,the higher reaction chamber pressure lead to the poor crystallinity.The ?/? flow rate also has a remarkable influence on the growth of zinc nitride thin films.