Bilayer graphene provides a versatile platform for exploring a variety of intriguing phenomena and shows much promise for applications in electronics,optoelectronics,etc.Controlled growth of large-area bilayer graphen...Bilayer graphene provides a versatile platform for exploring a variety of intriguing phenomena and shows much promise for applications in electronics,optoelectronics,etc.Controlled growth of large-area bilayer graphene is therefore highly desired yet still suffers from a slow growth rate and poor layer uniformity.Meanwhile,graphene wrinkles,including folds and ripples,form during cooling due to the thermal contraction mismatch between graphene and the metal substrates,and have been far from suppressed or eliminated,especially in bilayer graphene,which would greatly degrade the extraordinary properties of graphene.Here we report the ultrafast growth of wafer-scale fold-free bilayer graphene by chemical vapor deposition.Through well-tuning the alloy thickness and strain regulation of the single-crystal CuNi(111)/sapphire,the full coverage of a 2-inch fold-free bilayer graphene wafer via mainly isothermal segregation has been achieved as fast as 30 s.The tensile-strained CuNi(111)film reduces the thermal contraction mismatch and suppresses the formation of graphene folds during cooling,which is directly observed through in situ optical microscopy.The ultraflat bilayer graphene exhibits wafer-scale uniformity in electrical performance and enhanced mechanical property comparable to the exfoliated ones.Our results offer a promising route for largescale production of bilayer graphene and enable its various applications.展开更多
Wafer-scale graphene on SiC with uniform structural and electrical features is needed to realize graphene-based radio frequency devices and integrated circuits.Here,a continuous bi/trilayer of graphene with uniform st...Wafer-scale graphene on SiC with uniform structural and electrical features is needed to realize graphene-based radio frequency devices and integrated circuits.Here,a continuous bi/trilayer of graphene with uniform structural and electrical features was grown on 2 inch 6H-SiC (0001) by etching before and after graphene growth.Optical and atomic force microscopy images indicate the surface morphology of graphene is uniform over the 2 inch wafer.Raman and transmittance spectra confirmed that its layer number was also uniform.Contactless resistance measurements indicated the average graphene sheet resistance was 720 /with a non-uniformity of 7.2%.Large area contactless mobility measurements gave a carrier mobility of about 450 cm2 /(V s) with an electron concentration of about 1.5×10 13 cm2.To our knowledge,such homogeneous morphology and resistance on wafer scale are among the best results reported for wafer-scale graphene on SiC.展开更多
Scalable synthesis of transfer-free graphene over insulators offers exciting opportunity for next-generation electronics and optoelectronics.However,rational design of synthetic protocols to harvest wafer-scale produc...Scalable synthesis of transfer-free graphene over insulators offers exciting opportunity for next-generation electronics and optoelectronics.However,rational design of synthetic protocols to harvest wafer-scale production of directly grown graphene still remains a daunting challenge.Herein we explore a batch synthesis of large-area graphene with wafer-scale uniformity by virtue of direct chemical vapor deposition(CVD)on quartz.Such a controllable CVD approach allows to synthesize 30 pieces of 4-inch graphene wafers in one batch,affording a low fluctuation of optical and electrical properties.Computational fluid dynamics simulations reveal the mechanism of uniform growth,indicating thermal field and confined flow field play leading roles in attaining the batch uniformity.The resulting wafer-scale graphene enables the direct utilization as key components in optical elements.Our method is applicable to other types of insulating substrates(e.g.,sapphire,SiO2/Si,Si3N4),which may open a new avenue for direct manufacture of graphene wafers in an economic fashion.展开更多
The scalable growth of wafer-sized single-crystal graphene in an energy-efficient manner and compatible with wafer process is critical for the killer applications of graphene in high-performance electronics and optoel...The scalable growth of wafer-sized single-crystal graphene in an energy-efficient manner and compatible with wafer process is critical for the killer applications of graphene in high-performance electronics and optoelectronics. Here, ultrafast epitaxial growth of single-crystal graphene wafers is realized on singlecrystal Cu90Ni10(1 1 1) thin films fabricated by a tailored two-step magnetron sputtering and recrystallization process. The minor nickel(Ni) content greatly enhances the catalytic activity of Cu, rendering the growth of a 4 in. single-crystal monolayer graphene wafer in 10 min on Cu90Ni10(1 1 1), 50 folds faster than graphene growth on Cu(1 1 1). Through the carbon isotope labeling experiments, graphene growth on Cu90Ni10(1 1 1) is proved to be exclusively surface-reaction dominated, which is ascribed to the Cu surface enrichment in the Cu Ni alloy, as indicated by element in-depth profile. One of the best benefits of our protocol is the compatibility with wafer process and excellent scalability. A pilot-scale chemical vapor deposition(CVD) system is designed and built for the mass production of single-crystal graphene wafers, with productivity of 25 pieces in one process cycle. Furthermore, we demonstrate the application of single-crystal graphene in electrically controlled liquid-crystal microlens arrays(LCMLA), which exhibit highly tunable focal lengths near 2 mm under small driving voltages. By integration of the graphene based LCMLA and a CMOS sensor, a prototype camera is proposed that is available for simultaneous light-field and light intensity imaging. The single-crystal graphene wafers could hold great promising for highperformance electronics and optoelectronics that are compatible with wafer process.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.52021006,T2188101,and 22105009)Beijing National Laboratory for Molecular Sciences(No.BNLMSCXTD-202001)+1 种基金the Tencent Foundation(No.XPLORER PRIZE)We acknowledge Molecular Materials and Nanofabrication Laboratory(MMNL)in the College of Chemistry at Peking University for the use of instruments.
文摘Bilayer graphene provides a versatile platform for exploring a variety of intriguing phenomena and shows much promise for applications in electronics,optoelectronics,etc.Controlled growth of large-area bilayer graphene is therefore highly desired yet still suffers from a slow growth rate and poor layer uniformity.Meanwhile,graphene wrinkles,including folds and ripples,form during cooling due to the thermal contraction mismatch between graphene and the metal substrates,and have been far from suppressed or eliminated,especially in bilayer graphene,which would greatly degrade the extraordinary properties of graphene.Here we report the ultrafast growth of wafer-scale fold-free bilayer graphene by chemical vapor deposition.Through well-tuning the alloy thickness and strain regulation of the single-crystal CuNi(111)/sapphire,the full coverage of a 2-inch fold-free bilayer graphene wafer via mainly isothermal segregation has been achieved as fast as 30 s.The tensile-strained CuNi(111)film reduces the thermal contraction mismatch and suppresses the formation of graphene folds during cooling,which is directly observed through in situ optical microscopy.The ultraflat bilayer graphene exhibits wafer-scale uniformity in electrical performance and enhanced mechanical property comparable to the exfoliated ones.Our results offer a promising route for largescale production of bilayer graphene and enable its various applications.
基金supported by the National Basic Research Program of China(2011CB932700)the Knowledge Innovation Project of the Chinese Academy of Sciences(KJCX2-YW-W22)the National Natural Science Foundation of China(50972162and51072223)
文摘Wafer-scale graphene on SiC with uniform structural and electrical features is needed to realize graphene-based radio frequency devices and integrated circuits.Here,a continuous bi/trilayer of graphene with uniform structural and electrical features was grown on 2 inch 6H-SiC (0001) by etching before and after graphene growth.Optical and atomic force microscopy images indicate the surface morphology of graphene is uniform over the 2 inch wafer.Raman and transmittance spectra confirmed that its layer number was also uniform.Contactless resistance measurements indicated the average graphene sheet resistance was 720 /with a non-uniformity of 7.2%.Large area contactless mobility measurements gave a carrier mobility of about 450 cm2 /(V s) with an electron concentration of about 1.5×10 13 cm2.To our knowledge,such homogeneous morphology and resistance on wafer scale are among the best results reported for wafer-scale graphene on SiC.
基金This work was financially supported by the National Basic Research Program of China(No.2016YFA0200103)the National Natural Science Foundation of China(Nos.61527814,51702225,51432002,61474109,51290272,51502007,11474274,and 51672007)+2 种基金the National Equipment Program of China(No.ZDYZ2015-1)Beijing Municipal Science and Technology Planning Project(Nos.Z181100004818002 and Z191100000819004)Beijing Natural Science Foundation(No.4182063).
文摘Scalable synthesis of transfer-free graphene over insulators offers exciting opportunity for next-generation electronics and optoelectronics.However,rational design of synthetic protocols to harvest wafer-scale production of directly grown graphene still remains a daunting challenge.Herein we explore a batch synthesis of large-area graphene with wafer-scale uniformity by virtue of direct chemical vapor deposition(CVD)on quartz.Such a controllable CVD approach allows to synthesize 30 pieces of 4-inch graphene wafers in one batch,affording a low fluctuation of optical and electrical properties.Computational fluid dynamics simulations reveal the mechanism of uniform growth,indicating thermal field and confined flow field play leading roles in attaining the batch uniformity.The resulting wafer-scale graphene enables the direct utilization as key components in optical elements.Our method is applicable to other types of insulating substrates(e.g.,sapphire,SiO2/Si,Si3N4),which may open a new avenue for direct manufacture of graphene wafers in an economic fashion.
基金supported by the National Basic Research Program of China(2016YFA0200101 and 2014CB932500)the National Natural Science Foundation of China(21525310,51432002,51520105003,61432007,and 61176052)Beijing Municipal Science&Technology Commission(Z161100002116021 and Z181100004818001)
文摘The scalable growth of wafer-sized single-crystal graphene in an energy-efficient manner and compatible with wafer process is critical for the killer applications of graphene in high-performance electronics and optoelectronics. Here, ultrafast epitaxial growth of single-crystal graphene wafers is realized on singlecrystal Cu90Ni10(1 1 1) thin films fabricated by a tailored two-step magnetron sputtering and recrystallization process. The minor nickel(Ni) content greatly enhances the catalytic activity of Cu, rendering the growth of a 4 in. single-crystal monolayer graphene wafer in 10 min on Cu90Ni10(1 1 1), 50 folds faster than graphene growth on Cu(1 1 1). Through the carbon isotope labeling experiments, graphene growth on Cu90Ni10(1 1 1) is proved to be exclusively surface-reaction dominated, which is ascribed to the Cu surface enrichment in the Cu Ni alloy, as indicated by element in-depth profile. One of the best benefits of our protocol is the compatibility with wafer process and excellent scalability. A pilot-scale chemical vapor deposition(CVD) system is designed and built for the mass production of single-crystal graphene wafers, with productivity of 25 pieces in one process cycle. Furthermore, we demonstrate the application of single-crystal graphene in electrically controlled liquid-crystal microlens arrays(LCMLA), which exhibit highly tunable focal lengths near 2 mm under small driving voltages. By integration of the graphene based LCMLA and a CMOS sensor, a prototype camera is proposed that is available for simultaneous light-field and light intensity imaging. The single-crystal graphene wafers could hold great promising for highperformance electronics and optoelectronics that are compatible with wafer process.
