Undoped and V-doped 6H-SiC single crystals have been grown by the physical vapor transport method.The V concentration is determined to be 3.76×10^17 at/cm^3 and 6.14×10^17 at/cm^3 by secondary ion mass spect...Undoped and V-doped 6H-SiC single crystals have been grown by the physical vapor transport method.The V concentration is determined to be 3.76×10^17 at/cm^3 and 6.14×10^17 at/cm^3 by secondary ion mass spectrometry for low V-doped and high V-doped SiC samples,respectively.The undoped 6H-SiC shows diamagnetism,while the V-doped 6H-SiC exhibits weak ferromagnetism.The lower V-doped sample shows stronger ferromagnetism compared to that of the higher V-doped sample.However,the structural characterization indicates that the lower V-doped SiC has a relative poor crystalline quality.It is found that both V dopants and defects are essential for introducing ferromagnetic exchange in V-doped SiC single crystals.展开更多
This paper reports the sensitive effect of photoluminescence peak intensity and transmittance affected by B, Al, and N dopants in fluorescent 4H-SiC single crystals. The crystalline type, doping concentration, photolu...This paper reports the sensitive effect of photoluminescence peak intensity and transmittance affected by B, Al, and N dopants in fluorescent 4H-SiC single crystals. The crystalline type, doping concentration, photoluminescence spectra,and transmission spectra were characterized at room temperature. It is found that the doped 4H-SiC single crystal emits a warm white light covering a wide range from 460 nm to 720 nm, and the transmittance increases from ~10% to ~60%with the fluctuation of B, Al, and N ternary dopants. With a parameter of C_(D-A), defined by B, Al, and N concentration, the photoluminescence and transmittance properties can be adjusted by optimal doping regulation.展开更多
A Ni/Ta bilayer is deposited on n-type 6H–SiC and then annealed at different temperatures to form an ohmic contact. The electrical properties are characterized by I–V curve measurement and the specific contact resis...A Ni/Ta bilayer is deposited on n-type 6H–SiC and then annealed at different temperatures to form an ohmic contact. The electrical properties are characterized by I–V curve measurement and the specific contact resistance is extracted by the transmission line method. The phase formation and microstructure of the Ni/Ta bilayer are studied after thermal annealing. The crystalline and microstructure properties are analyzed by using glance incident x-ray diffraction（GIXRD）,Raman spectroscopy, and transmission electron microscopy. It is found that the transformation from the Schottky to the Ohmic occurs at 1050℃ and the GIXRD results show a distinct phase change from Ta2C to TaC at this temperature. A specific contact resistance of 6.5×10^-5Ω·cm^2is obtained for sample Ni（80 nm）/Ta（20 nm）/6H–SiC after being annealed at 1050℃. The formation of the TaC phase is regarded as the main reason for the excellent Ohmic properties of the Ni/Ta contacts to 6H–Si C. Raman and TEM data reveal that the graphite carbon is drastically consumed by the Ta element, which can improve the contact thermal stability. A schematic diagram is proposed to illustrate the microstructural changes of Ni/Ta/6H–SiC when annealed at different temperatures.展开更多
The 3C-SiC thin films used herein are grown on Si substrates by chemical vapor deposition. A1 contacts with differ- ent thickness values are deposited on the 3C-SiC/Si （100） structure by the magnetron sputtering met...The 3C-SiC thin films used herein are grown on Si substrates by chemical vapor deposition. A1 contacts with differ- ent thickness values are deposited on the 3C-SiC/Si （100） structure by the magnetron sputtering method and are annealed at different temperatures. We focus on the effects of the annealing temperature on the ohmic contact properties and mi- crostructure of A1/3C-SiC structure. The electrical properties of A1 contacts to n-type 3C-SiC are characterized by the transmission line method. The crystal structures and chemical phases of A1 contacts are examined by X-ray diffraction, Raman spectra, and transmission electron microscopy, respectively. It is found that the A1 contacts exhibit ohmic contact behaviors when the annealing temperature is below 550 ℃, and they become Schottky contacts when the annealing tem- perature is above 650 ℃. A minimum specific contact resistance of 1.8 × 10-4 Ω cm2 is obtained when the A1 contact is annealed at 250 ℃.展开更多
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 51002176)the Innovation Programs of the Chinese Academy of Sciences (Grant No. KJCX2-EW-W10)
文摘Undoped and V-doped 6H-SiC single crystals have been grown by the physical vapor transport method.The V concentration is determined to be 3.76×10^17 at/cm^3 and 6.14×10^17 at/cm^3 by secondary ion mass spectrometry for low V-doped and high V-doped SiC samples,respectively.The undoped 6H-SiC shows diamagnetism,while the V-doped 6H-SiC exhibits weak ferromagnetism.The lower V-doped sample shows stronger ferromagnetism compared to that of the higher V-doped sample.However,the structural characterization indicates that the lower V-doped SiC has a relative poor crystalline quality.It is found that both V dopants and defects are essential for introducing ferromagnetic exchange in V-doped SiC single crystals.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFB0405700 and 2016YFB0400400)the Young Scientists Fund of the National Natural Science Foundation of China(Grant Nos.51602331 and 61404146)the Shanghai Science and Technology Innovation Action Plan Program,China(Grant No.17511106200)
文摘This paper reports the sensitive effect of photoluminescence peak intensity and transmittance affected by B, Al, and N dopants in fluorescent 4H-SiC single crystals. The crystalline type, doping concentration, photoluminescence spectra,and transmission spectra were characterized at room temperature. It is found that the doped 4H-SiC single crystal emits a warm white light covering a wide range from 460 nm to 720 nm, and the transmittance increases from ~10% to ~60%with the fluctuation of B, Al, and N ternary dopants. With a parameter of C_(D-A), defined by B, Al, and N concentration, the photoluminescence and transmittance properties can be adjusted by optimal doping regulation.
基金Project supported by the Innovation Program of the Chinese Academy of Sciences(Grant No.KJCX2-EW-W10)the Shanghai Rising-star Program+3 种基金China(Grant No.13QA1403800)the Industry–Academic Joint Technological Innovations Fund Project of Jiangsu ProvinceChina(Grant No.BY2011119)the National High-tech Research and Development Program of China(Grant Nos.2013AA031603 and 2014AA032602)
文摘A Ni/Ta bilayer is deposited on n-type 6H–SiC and then annealed at different temperatures to form an ohmic contact. The electrical properties are characterized by I–V curve measurement and the specific contact resistance is extracted by the transmission line method. The phase formation and microstructure of the Ni/Ta bilayer are studied after thermal annealing. The crystalline and microstructure properties are analyzed by using glance incident x-ray diffraction（GIXRD）,Raman spectroscopy, and transmission electron microscopy. It is found that the transformation from the Schottky to the Ohmic occurs at 1050℃ and the GIXRD results show a distinct phase change from Ta2C to TaC at this temperature. A specific contact resistance of 6.5×10^-5Ω·cm^2is obtained for sample Ni（80 nm）/Ta（20 nm）/6H–SiC after being annealed at 1050℃. The formation of the TaC phase is regarded as the main reason for the excellent Ohmic properties of the Ni/Ta contacts to 6H–Si C. Raman and TEM data reveal that the graphite carbon is drastically consumed by the Ta element, which can improve the contact thermal stability. A schematic diagram is proposed to illustrate the microstructural changes of Ni/Ta/6H–SiC when annealed at different temperatures.
基金supported by the Shanghai Rising-Star Program,China(Grant No.13QA1403800)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.51002176)+2 种基金the Innovation Program of the Chinese Academy of Sciences(Grant No.KJCX2-EW-W10)the Industry–Academic Joint Technological Innovations Fund Project of Jiangsu Province,China(Grant No.BY2011119)the National High Technology Research and Development Program of China(Grant Nos.2013AA031603 and 2014AA032602)
文摘The 3C-SiC thin films used herein are grown on Si substrates by chemical vapor deposition. A1 contacts with differ- ent thickness values are deposited on the 3C-SiC/Si （100） structure by the magnetron sputtering method and are annealed at different temperatures. We focus on the effects of the annealing temperature on the ohmic contact properties and mi- crostructure of A1/3C-SiC structure. The electrical properties of A1 contacts to n-type 3C-SiC are characterized by the transmission line method. The crystal structures and chemical phases of A1 contacts are examined by X-ray diffraction, Raman spectra, and transmission electron microscopy, respectively. It is found that the A1 contacts exhibit ohmic contact behaviors when the annealing temperature is below 550 ℃, and they become Schottky contacts when the annealing tem- perature is above 650 ℃. A minimum specific contact resistance of 1.8 × 10-4 Ω cm2 is obtained when the A1 contact is annealed at 250 ℃.
