Study On Ohmic Contact Properties Of P-type GaP

Compound semiconductor materials,such as GaN,GaP and GaAs,have many advantages,such as wide bandgap,high electron mobility,high drift speed and high intrinsic resistivity.They are widely used in military radar,aerospace,optical fiber communication,lighting display and other fields.In the actual manufacturing process of semiconductor devices,besides the semiconductor materials themselves,it is often necessary to fabricate appropriate metal electrodes at the P and N ends of the semiconductor to transmit current signals.Therefore,how to obtain contact electrodes with stable properties and low resistivity is one of the factors that restrict the performance of semiconductor devices.In the past,the ohmic contact of GaN,GaAs and other semiconductors has been extensively studied.At present,AuBe alloy is widely used in the ohmic connection and reflection metals of P-type GaP of anti-polar red-light series LED.AuBe is not only expensive,but also highly toxic and environmentally unfriendly.In order to solve the above problems existing in anti-polar red-light LED,this paper mainly studies the cost,environmental friendliness and environmental friendliness.How Ag,Cu and P-type GaP with better reflectivity than AuBe form ohmic contact and formation mechanism,the main work and results are as follows:1.The theoretical mechanism of ohmic contact between semiconductor materials and metals is introduced.The advantages and disadvantages of common models for measuring specific contact resistivity are analyzed.Based on these,the model for measuring specific contact resistivity is determined.2.Referring to the mainstream metal electrode fabrication process,Ag,Ni/Ag,Cu,Ni/Cu,Au and Ni/Au electrodes were fabricated on the surface of p-type GaP.Good ohmic contact was obtained by annealing process.The effects of annealing temperature and annealing time,metal nickel and semiconductor surface state(material pretreatment)on the contact resistivity were studied,and the environment-friendly and specific contact resistivity were obtained.The electrochemical performance of the Ni/Ag electrode is better than that of the traditional gold beryllium electrode.3.The physical and chemical properties of contact electrodes and semiconductor materials before and after partial annealing were characterized by SIMS,XPS,SEM and AES.The mechanism of ohmic contact formed by GaP annealing and the variation of specific contact resistivity before and after annealing were explained.