We report the dc and rf performance of graphene rf field-effect transistors,where the graphene films are grown on copper by using the chemical vapour deposition (CVD) method and transferred to SiO2/Si substrates.Compo...We report the dc and rf performance of graphene rf field-effect transistors,where the graphene films are grown on copper by using the chemical vapour deposition (CVD) method and transferred to SiO2/Si substrates.Composite materials,benzocyclobutene and atomic layer deposition Al2O3 are used as the gate dielectrics.The observation of n- and p-type transitions verifies the ambipolar characteristics in the graphene layers.While the intrinsic carrier mobility of CVD graphene is extracted to be 1200cm2/V·s,the parasitic series resistances are demonstrated to have a serious impact on device performance.With a gate length of 1 μm and an extrinsic transconductance of 72 mS/mm,a cutoff frequency of 6.6 GHz and a maximum oscillation frequency of 8.8 GHz are measured for the transistors,illustrating the potential of the CVD graphene for rf applications.展开更多
Wafer-scale graphene field-effect transistors are fabricated using benzocyclobutene and atomic layer deposition Al_(2)O_(3) as the top−gate dielectric.The epitaxial-graphene layer is formed by graphitization of a 2-in...Wafer-scale graphene field-effect transistors are fabricated using benzocyclobutene and atomic layer deposition Al_(2)O_(3) as the top−gate dielectric.The epitaxial-graphene layer is formed by graphitization of a 2-inch-diameter Si-face semi-insulating 6H-SiC substrate.The graphene on the silicon carbide substrate is heavily n-doped and current saturation is not found.For the intrinsic characteristic of this particular channel material,the devices cannot be switched off.The cut-off frequencies of these graphene field-effect transistors,which have a gate length of 1µm,are larger than 800 MHz.The largest one can reach 1.24 GHz.There are greater than 95% active devices that can be successfully applied.We thus succeed in fabricating wafer-scale gigahertz graphene field-effect transistors,which paves the way for high-performance graphene devices and circuits.展开更多
文摘选用HZ016型阳离子交换树脂吸附甲基磺酸盐镀锡液中的锡和铁离子,以2 mol/L硫酸溶液洗脱树脂,通过调节洗脱液的p H来回收锡。结果表明,动态吸附锡和铁离子的效率均在95%以上,高于静态吸附。确定了吸附时树脂质量与镀液体积之比为1 g∶2 m L,洗脱时树脂质量与硫酸溶液体积之比为1 g∶4 m L。当调节洗脱液的p H至3.8时,锡的回收率达到87.5%,铁的残留率约为3%。
基金Supported by the National Science and Technology Major Project(No 2011ZX02707.3)the National Basic Research Program of China(2011CB921400)the National Natural Science Foundation of China under Grount Nos 61136005(Key Program),61006063 and 50772110.
文摘We report the dc and rf performance of graphene rf field-effect transistors,where the graphene films are grown on copper by using the chemical vapour deposition (CVD) method and transferred to SiO2/Si substrates.Composite materials,benzocyclobutene and atomic layer deposition Al2O3 are used as the gate dielectrics.The observation of n- and p-type transitions verifies the ambipolar characteristics in the graphene layers.While the intrinsic carrier mobility of CVD graphene is extracted to be 1200cm2/V·s,the parasitic series resistances are demonstrated to have a serious impact on device performance.With a gate length of 1 μm and an extrinsic transconductance of 72 mS/mm,a cutoff frequency of 6.6 GHz and a maximum oscillation frequency of 8.8 GHz are measured for the transistors,illustrating the potential of the CVD graphene for rf applications.
基金Supported by the National Science and Technology Major Project of China(2011ZX02707)the National Natural Science Foundation of China under Grant Nos 61136005 and 110761006063.
文摘Wafer-scale graphene field-effect transistors are fabricated using benzocyclobutene and atomic layer deposition Al_(2)O_(3) as the top−gate dielectric.The epitaxial-graphene layer is formed by graphitization of a 2-inch-diameter Si-face semi-insulating 6H-SiC substrate.The graphene on the silicon carbide substrate is heavily n-doped and current saturation is not found.For the intrinsic characteristic of this particular channel material,the devices cannot be switched off.The cut-off frequencies of these graphene field-effect transistors,which have a gate length of 1µm,are larger than 800 MHz.The largest one can reach 1.24 GHz.There are greater than 95% active devices that can be successfully applied.We thus succeed in fabricating wafer-scale gigahertz graphene field-effect transistors,which paves the way for high-performance graphene devices and circuits.
