scholarly journals Micro- and nanoscale electrical characterization of large-area graphene transferred to functional substrates

2013 ◽  
Vol 4 ◽  
pp. 234-242 ◽  
Author(s):  
Gabriele Fisichella ◽  
Salvatore Di Franco ◽  
Patrick Fiorenza ◽  
Raffaella Lo Nigro ◽  
Fabrizio Roccaforte ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Contact Resistance ◽  
Sheet Resistance ◽  
Flexible Electronics ◽  
Structural Integrity ◽  
Chemical Vapour ◽  
Specific Contact Resistance ◽  
Large Area ◽  
Conductive Atomic Force Microscopy ◽  
Specific Contact

Chemical vapour deposition (CVD) on catalytic metals is one of main approaches for high-quality graphene growth over large areas. However, a subsequent transfer step to an insulating substrate is required in order to use the graphene for electronic applications. This step can severely affect both the structural integrity and the electronic properties of the graphene membrane. In this paper, we investigated the morphological and electrical properties of CVD graphene transferred onto SiO2 and on a polymeric substrate (poly(ethylene-2,6-naphthalene dicarboxylate), briefly PEN), suitable for microelectronics and flexible electronics applications, respectively. The electrical properties (sheet resistance, mobility, carrier density) of the transferred graphene as well as the specific contact resistance of metal contacts onto graphene were investigated by using properly designed test patterns. While a sheet resistance R sh ≈ 1.7 kΩ/sq and a specific contact resistance ρc ≈ 15 kΩ·μm have been measured for graphene transferred onto SiO2, about 2.3× higher R sh and about 8× higher ρc values were obtained for graphene on PEN. High-resolution current mapping by torsion resonant conductive atomic force microscopy (TRCAFM) provided an insight into the nanoscale mechanisms responsible for the very high ρc in the case of graphene on PEN, showing a ca. 10× smaller “effective” area for current injection than in the case of graphene on SiO2.

scholarly journals Comparison of Electrical Properties of Ohmic Contact Realized on p-Type 4H-SiC

2008 ◽  
Vol 600-603 ◽  
pp. 639-642
Author(s):  
Duy Minh Nguyen ◽  
Christophe Raynaud ◽  
Mihai Lazar ◽  
Heu Vang ◽  
Dominique Planson
Keyword(s):  
Surface Roughness ◽  
Electrical Properties ◽  
Contact Resistance ◽  
Carrier Mobility ◽  
Ohmic Contacts ◽  
Series Resistance ◽  
Specific Contact Resistance ◽  
Specific Contact ◽  
P Type ◽  
Post Implantation

N+ 4H-SiC commercial substrates with n-type epilayers have been used to realize bipolar diodes and TLM structures. The p-type emitter of diodes was realized by Al implantations followed by a post-implantation annealing with or without a graphite capping layer. Ohmic contacts were formed by depositing Ti/Ni on the backside and Ni/Al on the topside of the wafer. It appears that capping the sample during the annealing reduces considerably the surface roughness and the specific contact resistance. Sheet resistance and specific contact resistance as low as 2kΩ/□ and respectively 1.75×10-4 Ωcm² at 300 K have been obtained. I-V measurements as a function of temperature have been performed from ~100 to ~500 K. The variations of the series resistance vs. temperature can be explained by the freeze-out of carriers and by the variation of carrier mobility.

Investigation of SET and RESET States Resistance in Ohmic Regime for Phase-Change Memory

2008 ◽  
Vol 1072 ◽  
Author(s):  
Semyon D. Savransky ◽  
Ilya V Karpov
Keyword(s):  
Electrical Properties ◽  
Contact Resistance ◽  
Phase Change ◽  
Phase Change Memory ◽  
Activation Energies ◽  
New Technique ◽  
Specific Contact Resistance ◽  
Bulk Conductivity ◽  
Specific Contact ◽  
Change Memory

ABSTRACTNew technique to separate bulk and interface electrical properties of polycrystalline and glassy Ge2Sb2Te5 (GST) in phase-change memory (PCM) devices is proposed. PCM with different GST thicknesses are measured. The average activation energies for bulk conductivity are 0.37 eV and 0.09 eV as well as bulk resistivities are about μOhm*cm2 and 20 μOhm*cm. The contact barriers is 0.07eV and specific contact resistance is about 0.3 μOhm*cm2 in studied PCM devices.It is discovered that bulk resistivities for both SET and RESET states in PCM obey Meyer-Neldel rule with almost identical isokinetic temperatures 335K − 340K. This information is discussed in terms of GST structure.

Aluminum Implantation in 4H-SiC: Physical and Electrical Properties

2013 ◽  
Vol 740-742 ◽  
pp. 581-584 ◽  
Author(s):  
Jean François Michaud ◽  
X. Song ◽  
J. Biscarrat ◽  
F. Cayrel ◽  
E. Collard ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Contact Resistance ◽  
Total Dose ◽  
Room Temperature ◽  
Microscopy Study ◽  
Specific Contact Resistance ◽  
Scanning Capacitance Microscopy ◽  
Aluminum Implantation ◽  
Specific Contact

For this study, 4H SiC samples were implanted with aluminum at room temperature, 200°C and 600°C with different energies, ranging from 30 to 380 keV, for a total dose of 4x1015 cm 2, to create a “box-like” profile. To activate dopants, samples were then isochronally annealed from 1650°C to 1850°C during 30min. The lowest specific contact resistance achieved, evaluated to 1.3x10-5 Ω.cm2, has been obtained for the 200°C implanted sample annealed at 1850°C. For this condition, Scanning Capacitance Microscopy study has proved that the dopant activity is quite homogeneous in opposition with the samples implanted at RT and 600°C.

Electrical Properties of (Zn, Mn) Containing Multilayer Metallizations to p-Type InGaAs/InP

1995 ◽  
Vol 382 ◽  
Author(s):  
Patrick W. Leec ◽  
Geoffrey K. Reeves ◽  
Wei Zhou
Keyword(s):  
Electrical Properties ◽  
Contact Resistance ◽  
Layer Thickness ◽  
Annealing Temperature ◽  
Specific Contact Resistance ◽  
Annealing Temperatures ◽  
Specific Contact ◽  
A Minor ◽  
P Type ◽  
Metal Layers

ABSTRACTThe specific contact resistance, pc, of Au/Zn/Au, Ni/Zn/Ni/Au, Pd/Zn/Pt/Au and Pd/Mln/Sb/Pd/Au contacts to p-In0.47Ga0.53As/ InP has been measured as a function of layer thickness of Zn or Mn. All of the as-deposited contacts were ohmic, with pc = 1−2 × 10−5 Ω cm2. Increasing thickness of the Zn layer above 200 Å in the Au/Zn/Au contacts resulted in a minor decrease in pc while producing no change in the Ni/Zn/Ni/Au metallization. For the as-deposited Pd/Mn/Pd/Au contacts, the value of pc was independent of thickness of the Mn layer but differences in pc emerged at annealing temperatures of ≥ 250°. The analysis of these structures by RBS has shown an extensive intermixing of the metal layers at an annealing temperature of 450 °. In the Pd/Zn/Pt/Au contacts, the value of pc was reduced to a minimum value of 8 × 10−6 Ω cm2 by annealing at a temperature of 500 °. An examination of the Pd/Zn/Pt/Au configuration by RBS has shown that the Pt layer acted as a barrier for the indiffusion of the Au.

High Temperature Characterization Of Ni, W And Al Contacts To 3C-Silicon Carbide Thin Films

1997 ◽  
Vol 483 ◽  
Author(s):  
C Jacob ◽  
P Pirouz ◽  
H-I Kuo ◽  
M Mehregany
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Contact Resistance ◽  
Room Temperature ◽  
Specific Contact Resistance ◽  
Large Area ◽  
Fermi Level Pinning ◽  
Specific Contact ◽  
Current Availability ◽  
Sic Films

AbstractWith the current availability of large-area 3C-SiC films, it is imperative that stable high temperature contacts be developed for high power devices. By comparing the existing data in the literature, we demonstrate that the contact behavior on each of the different polytypes of SiC will vary significantly. In particular, we demonstrate this for 6H-SiC and 3C-SiC. The interface slope parameter, S, which is a measure of the Fermi-level pinning in each system varies between 0.4–0.5 on 6H-SiC, while it is 0.6 on 3C-SiC. This implies that the barrier heights of contacts to 3C-SiC will vary more significantly with the choice of metal than for 6H-SiC.Aluminum, nickel and tungsten were deposited on 3C-SiC films and their specific contact resistance measured using the circular TLM method. High temperature measurements (up to 400°C) were performed to determine the behavior of these contacts at operational temperatures. Aluminum was used primarily as a baseline for comparison since it melts at 660°C and cannot be used for very high temperature contacts. The specific contact resistance (ρc) for nickel at room temperature was 5 × 10−4 Ω-cm2, but increased with temperature to a value of 1.5 × 10−3 Ω-cm2 at 400°C. Tungsten had a higher room temperature × 10−3 Ω-cm2, which remained relatively constant with increasing temperature up to 400°C. This is related to the fact that there is hardly any reaction between tungsten and silicon carbide even up to 900°C, whereas nickel almost completely reacts with SiC by that temperature. Contact resistance measurements were also performed on samples that were annealed at 500°C.

Optimization of Pd/Zn/Pd/Au Ohmic Contacts to p-Type inGaAs/ InP

1994 ◽  
Vol 337 ◽  
Author(s):  
Patrick W Leech ◽  
Geoffrey K. Reeves
Keyword(s):  
Thermal Stability ◽  
Electrical Properties ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Critical Thickness ◽  
Specific Contact Resistance ◽  
Zn Doping ◽  
Specific Contact ◽  
P Type ◽  
Thermal Stability Of

ABSTRACTThe electrical properties of Pd/Zn/Pd/Au based ohmic contacts to p-type In0 47Ga0 53As/ InP with an interposed superlattice of 50Å In047Gao 53As/ 50 Å InP have been investigated. In this study, several configurations of the Pd/Zn/Pd/Au metallization were fabricated with varying thicknesses of the Zn and interfacial Pd layers in the range 0 to 400 Å. The lowest values of specific contact resistance, ρc, were 1.2 x 10-5 Ω cm2 as-deposited and 7.5 x 106 Ω cm2 for samples annealed at 500 °C. In the as-deposited structures, ρc was reduced by an increase in thickness of both the Zn and Pd layers to 300 Å. For annealed samples, a critical thickness of the Zn ≥ 50 Å and Pd ≥ 100 Å layers was required in order to significantly reduce the magnitude of ρc. These results are consistent with a model of Pd/Zn contacts based on Zn doping of the interface. Studies of thermal stability of the contacts at 400 °C and 500 °C have shown that the Zn/Pd/Au and Pd/Zn/Pd/Au configurations were significanty lower in ρc at extended ageing times than the Pd/Au contacts.

Study of Optical and Electrical Properties of Ag/ITO Multi-Layer Transparent Electrodes

2013 ◽  
Vol 552 ◽  
pp. 162-167
Author(s):  
Min Rui Wang ◽  
Bin Yu ◽  
Yu Xia Wang
Keyword(s):  
Contact Resistance ◽  
Layer Thickness ◽  
Sheet Resistance ◽  
Annealing Temperature ◽  
Multilayer Films ◽  
Specific Contact Resistance ◽  
Optical And Electrical Properties ◽  
Ito Film ◽  
Current Voltage ◽  
Specific Contact

The samples of Ag/ITO multilayer films with different Ag insert layer thickness (0.5, 2, 4 nm) were prepared on sapphire and p-GaN substrates. The effects of the Ag layer thickness, annealing temperature and annealing time on the transmittance, sheet resistance and specific contact resistance of Ag/ITO films were investigated. The experiment results show that the transmittance is obviously affected by Ag insert layer thickness. The Current–voltage (I–V) measurements indicate that the sheet resistance and specific contact resistance of Ag/ITO film on p-GaN are lower than those of single ITO film. The samples with Ag(0.5nm)/ITO film on p-GaN produce the low specific contact resistance of ~1.386×10-4Ω•cm2 , low sheet resistance of ~11Ω/sq and high transmittance of ~ 90% at 455nm when the samples are annealed at 600°C for 10 minutes.

Evolution of Structural and Electrical Properties of Au/Ni Contacts onto P-GaN after Annealing

2012 ◽  
Vol 717-720 ◽  
pp. 1295-1298 ◽  
Author(s):  
Giuseppe Greco ◽  
Fabrizio Roccaforte ◽  
R. Lo Nigro ◽  
C. Bongiorno ◽  
S. Di Franco ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Contact Resistance ◽  
Nickel Oxide ◽  
Schottky Barrier Height ◽  
Specific Contact Resistance ◽  
Electrical Measurements ◽  
Rapid Annealing ◽  
Structural And Electrical Properties ◽  
Specific Contact ◽  
P Type

In this paper the structural and electrical evolution of Au/Ni contacts to p-type gallium nitride (GaN) upon annealing in different atmospheres was monitored. Rapid annealing of the contacts in an oxidizing atmosphere (N2/O2) resulted into a lower specific contact resistance (ρc) with respect to annealing in non-reacting ambient (Ar). The formation of a nickel oxide (NiO) layer was observed on the surface of the sample annealed in N2/O2 ,while was not present at the interface with p-GaN. The improvement of the contacts was associated with a reduction of the Schottky barrier height from 1.07 eV (Ar annealing) to 0.71 eV (N2/O2 annealing), as determined by the temperature dependence of the ρc. Local electrical measurements demonstrated the formation of inhomogeneous barriers. The electrical measurements were correlated with the different microstructure of the annealed contacts.

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