Low-Contact-Resistance Contacts to Graphene via Metal-Mediated Etching

2013 ◽  
Vol 1553 ◽  
Author(s):  
Wei Sun Leong ◽  
John T.L. Thong
Keyword(s):  
Contact Resistance ◽  
Promising Method ◽  
Pristine Graphene ◽  
Cmos Process ◽  
Metal Contacts ◽  
Ambient Conditions ◽  
Etching Technique ◽  
Graphene Devices

ABSTRACTThe theoretically-predicted enhancement of metal-graphene contacts using the “end-contacted” configuration is studied. Graphene edges at the source/drain regions are created via a CMOS process compatible metal-assisted etching technique. The on-resistance of a graphene device with cobalt-etched-graphene contacts shows 6 times improvement compared to pristine graphene device. Apart from that, four-point contacted graphene devices with nickel-etched-graphene contacts were fabricated and tested under ambient conditions. The proposed graphene devices exhibit contact resistance as low as 14 Ωμm, with an average of 90 Ωμm. Thus, forming metal-etched-graphene contacts is a promising method to obtain low-contact resistance metal contacts to graphene.

scholarly journals Influence of Humidity on Contact Resistance in Graphene Devices

2018 ◽  
Vol 10 (48) ◽  
pp. 41738-41746 ◽  
Author(s):  
Arne Quellmalz ◽  
Anderson D. Smith ◽  
Karim Elgammal ◽  
Xuge Fan ◽  
Anna Delin ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Graphene Devices

scholarly journals Effects of Different Ion Irradiation on the Contact Resistance of Pd/Graphene Contacts

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3928 ◽  
Author(s):  
Kashif Shahzad ◽  
Kunpeng Jia ◽  
Chao Zhao ◽  
Dahai Wang ◽  
Muhammad Usman ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Contact Resistance ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Chemical Reaction ◽  
Ion Irradiation ◽  
Metal Deposition ◽  
Pristine Graphene ◽  
Bombardment Energy ◽  
Induced Defects

The effect of ion-induced defects on graphene was studied to investigate the contact resistance of 40 nm palladium (Pd) contacting on graphene. The defect development was considered and analyzed by irradiating boron (B), carbon (C), nitrogen (N2), and argon (Ar) ions on as-transferred graphene before metallization. The bombardment energy was set at 1.5 keV and ion dose at 1 × 1014 ions/cm2. The defect yields under different ion irradiation conditions were examined by Raman spectroscopy. Although, dissolution process occurs spontaneously upon metal deposition, chemical reaction between metal and graphene is more pronounced at higher temperatures. The rapid thermal annealing (RTA) treatment was performed to improve the Pd/graphene contact after annealing at 450 °C, 500 °C, 550 °C, and 600 °C. The lowest contact resistance of 95.2 Ω-µm was achieved at 550 °C RTA with Ar ion irradiation. We have proved that ion irradiation significantly enhance the Pd/graphene contact instead of pd/pristine graphene contact. Therefore, in view of the contention of results ion induced defects before metallization plus the RTA served an excellent purpose to reduce the contact resistance.

scholarly journals Positioning of the Fermi Level in Graphene Devices with Asymmetric Metal Electrodes

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Bum-Kyu Kim ◽  
Eun-Kyoung Jeon ◽  
Ju-Jin Kim ◽  
Jeong-O Lee
Keyword(s):  
Fermi Level ◽  
Dirac Point ◽  
Metal Electrode ◽  
Peak Position ◽  
Metal Contacts ◽  
Metal Electrodes ◽  
Hole Band ◽  
Graphene Devices ◽  
Hybrid Devices ◽  
Bias Range

To elucidate the effect of the work function on the position of the Dirac point, we fabricated graphene devices with asymmetric metal contacts. By measuring the peak position of the resistance for each pair of metal electrodes, we obtained the voltage of the Dirac pointVgDirac(V) from the gate response. We found that the position ofVgDirac(V) in the hybrid devices was significantly influenced by the type of metal electrode. The measured shifts inVgDirac(V) were closely related to the modified work functions of the metal-graphene complexes. Within a certain bias range, the Fermi level of one of the contacts aligned with the electron band and that of the other contact aligned with the hole band.

An Approach to Improving the Morphology and Reliability of n-SiC Ohmic Contacts to SiC Using Second-Metal Contacts

2006 ◽  
Vol 527-529 ◽  
pp. 859-862 ◽  
Author(s):  
Matthew H. Ervin ◽  
Kenneth A. Jones ◽  
Un Chul Lee ◽  
Taniya Das ◽  
M.C. Wood
Keyword(s):  
Electrical Properties ◽  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Chemical Properties ◽  
Physical Contact ◽  
Metal Contacts ◽  
Critical Feature ◽  
Excess Carbon ◽  
Ohmic Contact Formation

While nickel ohmic contacts to n-type silicon carbide have good electrical properties, the physical contact, and therefore the reliability, can be poor. An approach is described for using the good electrical properties of Ni ohmic contacts while using another metal for its desired mechanical, thermal and/or chemical properties. In the present work, once the Ni contacts have been annealed forming nickel silicides and achieving low contact resistance, they are etched off. Removing the primary Ni contacts also eliminates the poor morphology, voids, and at least some of the excess carbon produced by the Ni/SiC reaction. The Ni contacts are then replaced by a second contact metal. This second metal displays low contact resistance as-deposited, indicating that the critical feature responsible for the ohmic contact has not been removed by the primary contact etch. Not only does this approach provide more flexibility for optimizing the contact for a given application, it also provides some insight into the ohmic contact formation mechanism.

A Scale Analysis Approach to Thermal Contact Resistance

2003 ◽  
Author(s):  
M. Bahrami ◽  
J. R. Culham ◽  
M. M. Yovanovich
Keyword(s):  
Contact Resistance ◽  
Entire Range ◽  
Thermal Contact Resistance ◽  
Present Model ◽  
Thermal Contact ◽  
Scale Analysis ◽  
Metal Contacts ◽  
Novel Approach ◽  
Wide Range ◽  
Data Points

A new analytical model is developed for predicting thermal contact resistance (TCR) of non-conforming rough contacts of bare solids in a vacuum. Instead of using probability relationships to model the size and number of microcontacts of Gaussian surfaces, a novel approach by employing the “scale analysis methods” is taken. It is shown that the mean size of the microcontacts is proportional to the surface roughness and inversely proportional to the surface asperity slope. A general relationship for determining TCR is derived by superposition of the macro and the effective micro thermal resistances. The present model allows TCR to be predicted over the entire range of non-conforming rough contacts from conforming rough to smooth Hertzian contacts. It is demonstrated that the geometry of heat sources on a half-space for microcontacts is justifiable and that effective micro thermal resistance is not a function of surface curvature. A comparison of the present model with 604 experimental data points, collected by many researchers during the last forty years, shows good agreement for the entire range of TCR. The data covers a wide range of materials, mechanical and thermophysical properties, micro and macro contact geometries, and similar and dissimilar metal contacts.

Chemical Vapor Deposited Graphene for Opto-Electronic Applications

2016 ◽  
Vol 39 ◽  
pp. 57-68
Author(s):  
Vikram Passi ◽  
Amit Gahoi ◽  
Sarah Riazimehr ◽  
Stefan Wagner ◽  
Andreas Bablich ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Spectral Response ◽  
Single Layer ◽  
Chemical Vapor ◽  
Adsorbed Water ◽  
Single Layer Graphene ◽  
Ambient Conditions ◽  
Transfer Length ◽  
Type Silicon ◽  
P Type

In this work, fabrication and characterisation of graphene photodiodes and transfer length method structures is presented. Graphene growth is carried out using a thermal chemical vapor deposition process on copper foils and subsequently transferred onto silicon-dioxide/silicon substrate. Comparison of electrical and optical characteristics of the photodiodes, which are fabricated on both n-type and p-type silicon, is shown. The photodiodes fabricated on n-type silicon show good rectifying behaviour when compared with photodiodes fabricated on p-type silicon. Spectral response of graphene photodiodes is measured to be less than 0.2 mAW-1 which is attributed to the light absorbance of 2.3% for single layer graphene. Transfer length method device structures are also fabricated and contact resistance is calculated and plotted as a function of spacing between the contacts. The calculated contact resistance (RcW) is 0.87 kΩ.µm. The latter structures are also characterised under various ambient conditions, before and after annealing. The value of contact resistance reduces from 0.87 kΩ.µm to 0.75 kΩ.µm after annealing. This reduction is attributed to the improvement in bonding between graphene and metal. Measurements under vacuum show an increase in contact resistance which is attributed to the removal of adsorbed water molecules on the surface on graphene. The sheet resistivity of graphene is calculated to be between 1.17 kΩ/□ and 3.67 kΩ/□.

Al/Ni And Al/Ti Ohmic Contact To P-type SiC Diffused Layer

2000 ◽  
Vol 640 ◽  
Author(s):  
Xaiobin Wang ◽  
Stanislav Soloviev ◽  
Ying Gao ◽  
G. Straty ◽  
Tangali Sudarshan ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Metal Contacts ◽  
Transfer Length ◽  
Type Layer ◽  
Transmission Line Method ◽  
Specific Contact ◽  
Background Doping ◽  
P Type

ABSTRACTOhmic contacts to p-type SiC were fabricated by depositing Al/Ni and Al/Ti followed by high temperature annealing. A p-type layer was fabricated by Al or B diffusion from vapor phase into both p-type and n-type substrates. The thickness of the diffused layer was about 0.1–0.2 μm with surface carrier concentration of about 1.0×1019cm−3. Metal contacts to a p-type substrate with a background doping concentration of 1.2×1018cm−3, without a diffusion layer, were also formed. The values of specific contact resistance obtained by Circular Transmission Line Method (CTLM) and Transfer Length Method (TLM) for the n-type substrate, and by Cox & Strack method for p-type substrate, respectively, varied from 1.3×10−4Ωcm2 to 8.8×10−3 Ωcm2. The results indicate that the specific contact resistance could be significantly reduced by creating a highly doped diffused surface layer.

Characterization of Contact Resistance between Carbon Nanotubes Film and Metal Electrodes

2013 ◽  
Vol 683 ◽  
pp. 238-241
Author(s):  
Ki Bong Han ◽  
Yong Ho Choi
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Contact Resistance ◽  
Chemical Properties ◽  
Metal Electrode ◽  
Metal Contacts ◽  
Metal Electrodes ◽  
3 Dimensional ◽  
Current Path ◽  
Classical Technique

Carbon nanotube has attracted great research attentions due to its outstanding electrical, physical, mechanical, chemical properties. Based on its excellent properties, the carbon nanotube is promising nanoscale material for novel electrical, mechanical, chemical, and biological devices and sensors. However, it is very difficult to control the structure of carbon nanotube during synthesis. A carbon nanotubes film has 3 dimensional structures of interwoven carbon nanotubes as well as unique properties such as transparency, flexibility and good electrical conductivity. More importantly, the properties of carbon nanotubes are ensemble averaged in this formation. In this research, we study the contact resistance between carbon nanotubes film and metal electrode. For most of electrical devices using carbon nanotubes film, it is necessary to have metal electrodes on the film for current path. A resistance at the contact lowers the electrical efficiencies of the devices. Therefore, it is important to measure and characterize the contact resistance and lower it for better efficiencies. The device demonstrated in this study using classical technique for metal contacts provides relatively reliable contact resistance measurements for carbon nanotubes film applications.

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