The nitrogen ions implanted layer of p type 4H SiC epilayer is investigated.The fabrication processes and measurements of the implanted layer are given in details.The profile of implantation depth is simulated using the Monte Carlo simulator TRIM.Lateral Schottky barrier diodes and transfer length method (TLM) measurement structure are made on nitrogen implanted layers for the testing.The concentration of activated donors N d is about 3 0×10 16 cm -3 .The resulting value for the activation rate in this study is 2 percent.The sheet resistance R sh is 30kΩ/□ and the resistivity ρ(R sh × d ) of the implanted layer is 0 72Ω·cm.The electron mobility calculated is about 300cm 2/(V·s) in the N implanted layer.
A precise theoretical calculation off the pinch of voltage of the box-like ion implantation 4H-SiC MESFETs is investigated with the consideration of the effects of the ion-implanted channel and the depth of MESFETs channel.The implant depth profile is simulated using the Monte Carlo simulator TRIM.The effects of parameters such as temperature,acceptor density,and activation rate on channel depth a,pinch off voltage are studied.
For very high temperature annealing (1620℃) after ion implantation for 4H silicon carbide (4H SiC),the residual components of Al and O in the alundum furnace impact seriously on the surface of material,which yields the derivation of SiOC.This causes a significant degradation of the 4H SiC surface characteristics according to the results of surface composition analysis.As validity,Ni/SiC ohmic contact measurement illustrates a higher specific contact resistance than the normal value by a factor of 2～3.Consequently the MESFET fabricated with this kind of 4H SiC material results in a degraded I V output performance compared with that of normal 4H SiC MESFET.
