The Fabrication Of Gallium Oxide Based Schottky Barrier Diodes And MESFETs

Since the 21st century,power electronics technology has been developed for a long time,and it has been widely used in electric power systems,new energy resources,communications,ocean transportation,and space exploration.However,due to the limitations of silicon(Si)materials,Si-based power devices have been unable to meet the requirements for applications such as o cean transportation,space exploration,and deep good exploration.Power devices with third-generation semiconductor materials silicon carbide(Si C)and gallium nitride(Ga N)as the core have been relatively mature in wafer growth and process fabrication,and have been gradually put into the market in recent years.However,the growth and processes of Si C and Ga N need high-temperature and high-pressure conditions.Gallium oxide(Ga₂O₃),the fourth-generation semiconductor material,has attracted a lot of at tention in recent years,mainly because it can be grown by an economical melt method to obtain a large area and high-quality single crystal substrate.Therefore,the Ga₂O₃-based power devices have attracted the attention of governments,enterprises,and research institutions around the world,especially the Ga ₂O₃-based power diodes and field effect transistors.However,the current domestic and foreign researchers mainly focus on the fabrication and performance improvement of(Metal insulator semiconductor filed effect transistors)MISFETs,less attention is paid to(Metal semiconductor filed effect transistors)MESFETs.Therefore,this article relies on the“Huxiang High-level Talents Focus Engineering-Innovative Talents(Xiangke Talent[2019]No.7)”for the fabrication and characterization of Ga₂O₃-based power diodes and MESFETs.In this paper,firstly,the lateral Au/Ga₂O₃ Schottky barrier diodes were fabricated on a high-quality gallium oxide substrate through a standard device process.the barrier height and ideality factor were extracted at room temperature.These devices exhibited extremely high output current(1 k A/cm²),on/off ratio(>10⁹),and low reverse leakage current(10^-6 A/cm²).In addition,we studied the thermal stability of Ga₂O₃ Schottky barrier diodes.When the devices were annealed at 200-400°C,we found that these devices still maintain a higher output current and a lower reverse current after annealing.Moreover,the barrier height and ideality factor of these devices remained stable,indicating that the devices have high thermal stability.Secondly,Ga₂O₃ MESFETs devices were fabricated based on the assembly of Schottky barrier diodes.The results show that these devices have a high output current density(46.8 m A/mm).The threshold voltage is extracted to be-9.7 V at room temperature,the maximum transconductance is 7.7 m S/mm,which proves that these devices have excellent electrical properties.Then,this paper studies the effects of different gate length on the electrical properties of Ga ₂O₃ MESFETs.As the gate length increases,the maximum output current of these devices decreases,and the transconductance also decreases gradually.Finally,this article studies the thermal stability of Ga ₂O₃ MESFETs.These devices are annealed at 200°C,300°C,and 400°C after the deposition of the gate metal,respectively.After annealing,the maximum output current of the drain electrode of the device increases as the annealing temperature,and the threshold voltage gradually increases.However,when these devices are annealed at 400°C,they encountered serious leakage current.At a large reverse gate voltage and the drain voltage at 6V,the output current of the device suddenly rises sharply,leading to the normally-off phenomenon.This might be caused by th e deterioration of the quality of the interface between semiconductor and metal.In summary,this article mainly introduces the working principle,preparation process,and electrical characterization of gallium oxide Schottky diodes and MESFETs.The results indicated that the devices have excellent electrical characteristics.In addition,this article also studies and discusses the effect of annealing temperature on the electrical characteristics of the Ga ₂O₃Schottky diodes and MESFETs in detail.