共查询到19条相似文献,搜索用时 140 毫秒
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对n型SiC的Ni基欧姆接触的机理进行了研究.通过在P型4H-SiC外延层上使用N离子注入来形成N阱,并在此基础上制作Ni/n型SiC欧姆接触的TLM结构,得到的比接触电阻约为1.7X10-4Ω·cm2.合金化的高温退火过程导致了C空位(Vc)的出现,起到了施主的作用,降低了有效肖特基势垒高度,从而形成欧姆接触.通过模拟估计了有效载流子密度的增加,结果表明,高温退火中形成的C空位对于最终欧姆接触的形成起到了重要作用,甚至超过了掺杂水平的影响. 相似文献
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研究了n型碳化硅(SiC)极性表面、载流子浓度和退火温度对欧姆接触的影响,测试了不同样品的电流-电压曲线,并通过传输线方法计算比接触电阻。对于SiC衬底的硅面,GeNiTiAu合金材料的欧姆接触特性最好;而对于碳面,TiAu合金材料的接触电阻最小。衬底载流子浓度由1.5×101 7cm-3逐步提高到2.0×1018cm-3,金属与n型SiC衬底硅面的接触由肖特基接触变为欧姆接触,欧姆接触电阻随着载流子浓度的提高而明显降低。GeTiAu合金与SiC衬底硅面的接触电阻随着退火温度的提高非单调降低,900℃为最优退火温度。原子力显微镜结果显示,退火后样品表面粗糙度明显提高。 相似文献
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研究了Ni/Pt和Ti/Pt金属在n型4H-SiC上的欧姆接触。在1 020℃退火后,Ni/Pt与n型4H-SiC欧姆接触的比接触电阻为2.2×10-6Ω·cm2。Ti/Pt与n型4H-SiC欧姆接触的比接触电阻为5.4×10-6Ω·cm2,退火温度为1 050℃。虽然Ni的功函数比Ti的功函数高,但是Ni比Ti更容易与n型4H-SiC形成欧姆接触。使用能谱分析仪(EDX)分析了Ni/Pt和Ti/Pt金属与4HSiC接触面的元素,观察到C原子相对于Pt原子的原子数分数随退火温度的变化而不同。实验验证了在n型4H-SiC中退火导致的碳空位起施主作用是有利于欧姆接触形成的主要原因。 相似文献
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借助二次离子质谱法分析了注入的钒离子在碳化硅中的分布.即使经过1650℃的高温退火,钒在碳化硅中的再扩散也不显著.退火并没有导致明显的钒向碳化硅表面扩散形成堆积的现象,由于缺少钒的补偿作用,表面薄层的自由载流子浓度保持不变.采用线性传输线模型测量了钒注入n型4H-SiC上的Ni基接触电阻,在1050℃下,在氮、氢混合气体中退火10min,形成的最低比接触电阻为4.4×10-3Ω·cm2.金属化退火后的XRD分析结果表明,镍、碳化硅界面处形成了Ni2Si和石墨相.观测到的石墨相是由于退火导致C原子外扩散并堆积形成,同时在碳化硅表面形成C空位.C空位可以提高有效载流子浓度,降低势垒高度并减小耗尽层宽度,对最终形成欧姆接触起到了关键作用. 相似文献
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借助二次离子质谱法分析了注入的钒离子在碳化硅中的分布.即使经过1650℃的高温退火,钒在碳化硅中的再扩散也不显著.退火并没有导致明显的钒向碳化硅表面扩散形成堆积的现象,由于缺少钒的补偿作用,表面薄层的自由载流子浓度保持不变.采用线性传输线模型测量了钒注入n型4H-SiC上的Ni基接触电阻,在1050℃下,在氮、氢混合气体中退火10min,形成的最低比接触电阻为4.4×10-3Ω·cm2.金属化退火后的XRD分析结果表明,镍、碳化硅界面处形成了Ni2Si和石墨相.观测到的石墨相是由于退火导致C原子外扩散并堆积形成,同时在碳化硅表面形成C空位.C空位可以提高有效载流子浓度,降低势垒高度并减小耗尽层宽度,对最终形成欧姆接触起到了关键作用. 相似文献
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基于圆形传输线模型,研究了背景载流子浓度为71016cm3的非故意掺杂GaN与Ti/Al/Ni/Au多层金属之间欧姆接触的形成。样品在N2气氛中,分别经过温度450,550,700,800,900℃的1 min快速热退火处理后发现,当退火温度高于700℃欧姆接触开始形成,随着温度升高欧姆接触电阻持续下降,在900℃时获得了最低比接触电阻6.6106O·cm2。研究表明,要获得低的欧姆接触电阻,需要Al与Ti发生充分固相反应,并穿透Ti层到达GaN表面;同时,GaN中N外扩散到金属中,在GaN表面产生N空位起施主作用,可提高界面掺杂浓度,从而有助于电子隧穿界面而形成良好欧姆接触。 相似文献
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4H-SiC欧姆接触与测试方法研究 总被引:1,自引:1,他引:0
主要针对不同金属和工艺条件下的4H-SiC欧姆接触特性进行对比研究,形成4H-SiC的优良欧姆接触的最佳条件。通过TLM方法结合四探针测量得到特征接触电阻率,测得NiCr和Ni与4H-SiC的最佳特征接触电阻率分别达到ρc=9.02×10-6Ω.cm2,ρc=2.22×10-7Ω.cm2,能够很好满足SiC器件的需要。 相似文献
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M. Gao S. Tsukimoto S.H. Goss S.P. Tumakha T. Onishi M. Murakami L.J. Brillson 《Journal of Electronic Materials》2007,36(4):277-284
We have investigated the roles of interfacial reaction, work function variation, and localized states of annealed Ti/Al ohmic
contacts to p-type 4H-SiC. The Al was found to be absent in the near interface region. The possibility of additional p-doping by Al indiffusion in the top SiC layer was ruled out. The work function of Ti3SiC2, the direct contact layer to SiC, was determined to be intermediate between Ti and p-SiC, leading to a considerably lowered Schottky barrier height. Reaction-induced interfacial states were observed in the near-interface
SiC, which may further reduce the barrier height and cause the formation of ohmic contact. 相似文献
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We report the effect of the Pt barrier on the thermal stability of Ti/Al/Pt/Au in ohmic contact with Si-implanted n-type GaN
layers. Ti/Al/Au (25/100/200 nm) and Ti/Al/Pt/Au (25/100/50/200 nm) multilayers were, respectively, deposited on as-implanted
and recovered Si-implanted n-type GaN samples. The associated dependence of the specific contact resistance on the annealing
time at various temperatures was compared. The long-term ohmic stability of a Ti/Al/Pt/Au multilayer in contact with a Si-implanted
n-type GaN layer was much better than that of the Ti/Al/Au multilayer. This superior stability is attributed to the barrier
function of the Pt interlayer. The Pt/Au bilayer can also passivate the propensity of oxidation for the conventional Ti/Al
bilayer in contact with n-type GaN layers at elevated temperatures. 相似文献
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The electrical contact properties of Co/4H-SiC structures are investigated.A carbon interfacial layer between a Co film and SiC is used to improve the Ohmic contact properties significantly.The C film is deposited prior to Co film deposition on SiC using DC sputtering.The high quality Ohmic contact and specific contact resistivity of 2.30×10-6Ω·cm2 are obtained for Co/C/SiC structures after two-step annealing at 500℃for 10 min and 1050℃for 3 min.The physical properties of the contacts are examined by using XRD.The results indicate that the Co-based metal contacts have better structural stability of silicide phases formed after the high temperature annealing and carbon-enriched layer is produced below the contact,playing a key role in forming an Ohmic contact through the reduction of effective Schottky barrier height for the transport of electrons.The thermal stability of Au/Co/C/SiC Ohmic contacts is investigated.The contacts remain Ohmic on doped n-type(2.8×1018 cm-3) 4H-SiC after thermal aging treatment at 500℃for 20 h. 相似文献
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H. Fathollahnejad R. Rajesh J. Liu R. Droopad G. N. Maracas R. W. Carpenter 《Journal of Electronic Materials》1995,24(1):35-38
A low resistance PdGe nonalloyed ohmic contact has been successfully formed to epitaxially lifted-off n-type GaAs films. The
contact is made by lifting off partially metallized n-type GaAs films using the epitaxial lift-off method and bonding them
to metallized Si substrates by natural intermolecular Van Der Waals forces. Low temperature sintering (200°C) of this contact
results in metallurgical bonding and formation of the ohmic contact. We have measured specific contact resistances of 5 ×
10−5 Ω-cm2 which is almost half the value obtained for pure Pd contacts. Germanium forms a degenerately doped heterojunction interfacial
layer to GaAs. Our experimental results show that germanium diffuses to the interface and acts as a dopant layer to n-GaAs
film surface. Therefore, for epitaxially lifted-off n-type GaAs films, PdGe is a low resistance ohmic metal contact to use. 相似文献
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Kelner G. Shur M.S. Binari S. Sleger K.J. Kong H.-S. 《Electron Devices, IEEE Transactions on》1989,36(6):1045-1049
An improved performance buried-gate SiC junction field-effect transistor (JFET) has been fabricated and evaluated. This structure uses an n-type β-SiC film epitaxially grown by chemical vapor deposition on the Si(0001) face of a p-type 6H α-SiC single crystal. The current in the n-type channel was modulated using the p-type α-SiC layer as a gate. Electron-beam-evaporated Ti/Au was utilized as an ohmic contact to the n-type β-SiC layer, and thermally evaporated Al was used to contact the p-type gate. A maximum DC transconductance of 20 mS/mm was obtained, which is the highest reported for a β-SiC FET structure. The experimental data are analyzed using a charge-control model. Calculated drain current versus drain voltage characteristics for a buried-gate JFET are in good agreement with experimental data 相似文献
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E. D. Luckowski J. M. Delucca J. R. Williams S. E. Mohney M. J. Bozack T. Isaacs-Smith J. Crofton 《Journal of Electronic Materials》1998,27(4):330-334
Results are reported for ohmic contacts formed on n-type 4H and 6H-SiC using nichrome (80/20 weight percent Ni/Cr). The electrical
characteristics of these NiCr contacts are similar to those of contacts formed on 6H-SiC using pure Ni (∼1×10−5Ω-cm2 for moderately doped material), but the contacts exhibit significant improvement with regard to physical stability. Composite
Au/NiCr contacts exhibit good stability during long-term anneals (∼2500 h) at 300°C without the requirement of a diffusion
barrier layer between the NiCr ohmic contact layer and the Au cap layer. In addition, the use of NiCr results in success rates
near 100% for direct wire bonding to the Au cap layers. Characterization of the contacts by Auger electron spectroscopy, Rutherford
backscattering spectroscopy, and transmission electron microscopy provides an explanation for the observed behavior. 相似文献