Fabrication And Study Of Ge-doped Ga N-based Vertical Schottky Barrier Diode

Power electronic devices,known as power semiconductor devices,are high-power electronic devices which mainly used in power conversion and control circuits of power equipment.They are widely used in household appliances,industrial power supplies,motor drives,power traction,power quality control,renewable energy power generation,distributed power generation,national defense,and cutting-edge science and technology.Schottky barrier diode is one of the most essential power components in power electronic device.As a third-generation wide band gap semiconductor,GaN is not only a direct band gap material,but also has a wide band gap and high breakdown electric field.At the same time,GaN has excellent thermal conductivity and high temperature resistance.These advantages significantly make up for the inherent shortcomings of the previous two generations semiconductor materials.So GaN is an ideal material for preparing high temperature,high power and frequency,radiation resistant electronic devices and short wavelength,high power optoelectronic devices.Si,as a traditional dopant for n-type GaN,especially for heavily doped GaN substrates,will significantly increase its internal stress,resulting in a corresponding increase in crystal defects,which cannot meet the requirements of high-quality devices.As a shallow-level donor,Ge not only has activation energy close to that of Si(Ge?20 me V,Si?17 me V),but also has an atomic radius close to Ga,which can further reduce the deformation caused by its doping.Therefore,the Ge-doped GaN substrate has lower stress and defects.Based on the Ge-doped GaN substrate,this paper studies the Ge-doped GaN vertical Schottky barrier diode through material characterization,theoretical analysis,device preparation,and electrical testing.Firstly,AFM,HRXRD,Raman,PL,CL,and other equipments were used to perform characterization of Ge-doped GaN.It was verified that the Ge-doped GaN has good crystal quality,and the discussion proved that Ge-doped GaN has less internal stress than Si-doped commonly used.Secondly,a Ge-doped GaN vertical Schottky barrier diode was prepared based on the ohmic contact preparation process of GaN.Through various electrical tests,the fundamental parameters were indicated that the Ge-doped GaN vertical Schottky barrier diode has perfect Schottky contact and reverse breakdown features.Besides,the reverse recovery current test proves that Ge-doped GaN vertical Schottky barrier diodes have excellent stability at high temperatures.Finally,the Ge-doped GaN vertical Schottky barrier diode was subjected to O₂Plasma treatment.The native oxide termination structure as a passivation layer was prepared on the Ge-doped GaN vertical Schottky barrier diode.It was found that it not only has the function of removing pollution but also plays a role in adjusting the electric field lines and improving the breakdown field strength.Thus,O₂ Plasma process enhance the stability of the device.