Four kinds of SiC fibers with different specific resistivities were prepared by the pyrolysis of cured polycarbosilane fiber. The results show that SiC fibers with different specific resistivities can be obtained by c...Four kinds of SiC fibers with different specific resistivities were prepared by the pyrolysis of cured polycarbosilane fiber. The results show that SiC fibers with different specific resistivities can be obtained by changing the curing and pyrolysis conditions. And the free carbon content and the ability to crystallize no longer affect the specific resistivities notably with the time when the fiber is covered with an excess carbon layer, and the fiber has a low specific resistivity. The excess carbon layer in the circular outer part is originated from the re-pyrolysis and deposition of hydrocarbon volatiles. The removal of the carbon by oxidative treatment may affect the surface property and also promote the magnitude of specific resistivity. The influence of the surface property on the specific resistivity can be considerable and should not be neglected.展开更多
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 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.展开更多
The effects of several factors on mobility in 4H-SiC buried-channel （BC） MOSFETs are studied,A simple model that gives a quantitative analysis of series resistance effects on the effective mobility and field-effect ...The effects of several factors on mobility in 4H-SiC buried-channel （BC） MOSFETs are studied,A simple model that gives a quantitative analysis of series resistance effects on the effective mobility and field-effect mobility is proposed.A series resistance not only decreases field-effect mobility but also reduces the gate voltage corresponding to the peak field-effect mobility. The dependence of the peak field-effect mobility on series resistance follows a simple quadratic polynomial. The effects of uniform and exponential interface state distributions in the forbidden band on field-effect mobility are analyzed with an analytical model. The effects of non-uniform interface states can be ignored at lower gate voltages but become more obvious as the gate bias increases.展开更多
Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si...Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.展开更多
文摘Four kinds of SiC fibers with different specific resistivities were prepared by the pyrolysis of cured polycarbosilane fiber. The results show that SiC fibers with different specific resistivities can be obtained by changing the curing and pyrolysis conditions. And the free carbon content and the ability to crystallize no longer affect the specific resistivities notably with the time when the fiber is covered with an excess carbon layer, and the fiber has a low specific resistivity. The excess carbon layer in the circular outer part is originated from the re-pyrolysis and deposition of hydrocarbon volatiles. The removal of the carbon by oxidative treatment may affect the surface property and also promote the magnitude of specific resistivity. The influence of the surface property on the specific resistivity can be considerable and should not be neglected.
文摘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.
文摘The effects of several factors on mobility in 4H-SiC buried-channel （BC） MOSFETs are studied,A simple model that gives a quantitative analysis of series resistance effects on the effective mobility and field-effect mobility is proposed.A series resistance not only decreases field-effect mobility but also reduces the gate voltage corresponding to the peak field-effect mobility. The dependence of the peak field-effect mobility on series resistance follows a simple quadratic polynomial. The effects of uniform and exponential interface state distributions in the forbidden band on field-effect mobility are analyzed with an analytical model. The effects of non-uniform interface states can be ignored at lower gate voltages but become more obvious as the gate bias increases.
文摘Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.
