scholarly journals Specific contact resistance of ohmic contacts to n-type SiC membranes

2011 ◽  
Vol 1335 ◽  
Author(s):  
N.F. Mohd Nasir ◽  
A.S. Holland ◽  
G.K. Reeves ◽  
P.W. Leech ◽  
A. Collins ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Current Flow ◽  
Specific Contact Resistance ◽  
Voltage Response ◽  
Metal Contacts ◽  
Transmission Line Model ◽  
Si Substrate ◽  
Current Voltage ◽  
Specific Contact

ABSTRACTMembranes of epitaxial SiC have been used as a means of eliminating the leakage current into the Si substrate during circular transmission line model (CTLM) measurements. In the n+-3C-SiC/Si wafers, the Si substrate was etched in a patterned window with dimensions up to 10 mm × 15 mm2. An array of CTLM metal contacts was then deposited onto the upper surface of the n+-SiC membrane. The CTLM contacts on the membrane have shown an ohmic current/voltage response while electrodes located on the adjacent substrate were non-ohmic. Values of ρc were measured directly on the membranes. These results have shown a significant increase in the current flow below the metal contacts due to the presence of the Si substrate.

Properties of Al and Pd Contacts on n-type SiC Membranes

2012 ◽  
Vol 1433 ◽  
Author(s):  
N.F. Mohd Nasir ◽  
P.W. Leech ◽  
A.S. Holland ◽  
G.K. Reeves ◽  
P. Tanner
Keyword(s):  
Contact Resistance ◽  
Silicon Surfaces ◽  
Specific Contact Resistance ◽  
Voltage Response ◽  
Consistent Difference ◽  
Metal Contacts ◽  
Ion Etching ◽  
Current Voltage ◽  
Specific Contact ◽  
Etched Silicon

ABSTRACTMembranes with dimensions up to 10 mm x 15 mm have been fabricated in epitaxial 3C-SiC/Si wafers. An array of CTLM metal contacts was deposited onto the upper surface of the n-SiC membrane. Both Al/n-SiC and Pd/n-SiC contacts which were formed on the membrane and on the adjacent substrate have shown an ohmic current/ voltage response. Values of specific contact resistance, ρc, were measured directly on the membranes. These results have shown no consistent difference in ρc of the contacts located either on the membrane or off the membrane. The exposure of SiC surfaces to reactive ion etching in CF4 plasma during the fabrication of a membrane has resulted in ρc which was higher by a factor of 103 than with as-grown and KOH etched silicon surfaces.

Modelling Geometrical Effects of Parasitic and Contact Resistance of FET Devices

1996 ◽  
Vol 427 ◽  
Author(s):  
Geoffrey K. Reeves ◽  
H. Barry Harrison ◽  
Patrick W. Leech
Keyword(s):  
Contact Resistance ◽  
Material Properties ◽  
Ohmic Contacts ◽  
Difficult Problem ◽  
Specific Contact Resistance ◽  
Metal Silicide ◽  
Transmission Line Model ◽  
Specific Contact ◽  
Geometrical Effects ◽  
Contact Parameters

AbstractThe continual trend in decreasing the dimensions of semiconductor devices results in a number of technological problems. One of the more significant of these is the increase in contact resistance, Rc. In order to understand and counteract this increase, Rc needs to be quantitatively modelled as a function of the geometrical and material properties of the contact. However the use of multiple semiconductor layers for ohmic contacts makes the modelling and calculation of Rc a more difficult problem. In this paper, a Tri-Layer Transmission Line Model (TLTLM) is used to analyse a MOSFET ohmic contact and gatedrain region. A quantitative assessment of the influence on Rc of important contact parameters such as the metal-silicide specific contact resistance, the silicide-silicon specific contact resistance and the gate-drain length can thus be made. The paper further describes some of the problems that may be encountered in defining Rc when the dimensions of certain types of contact found in planar devices decrease.

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.

Ohmic Contacts on N-Type Hg0.4Cd0.6Te.

1990 ◽  
Vol 216 ◽  
Author(s):  
Patrick W. Leech ◽  
Geoffrey K. Reeves ◽  
Martyn H. Kibel
Keyword(s):  
Contact Resistance ◽  
Transmission Line ◽  
Schottky Barrier ◽  
Optical Communications ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Electrical Characteristics ◽  
Schottky Barrier Diodes ◽  
Transmission Line Model ◽  
Specific Contact

ABSTRACTThe electrical characteristics of In, Sn, Au and Pt contacts on n-type Hg0.4Cd0.6Te formed in the presence and absence of prior In2+ implantation have been examined. Measurements of specific contact resistance made using a Transmission Line Model have shown that the unimtlanted In/Hg0.4Cd0.6 and Sn/Hg0.4Cd0.6 junctions gave values of pc = 3.0x10−3 to 4.0x10−3 ohm.cm2. Auger sputter profiles of the asdeposited In/Hg0.4Cd0.6 and Sn/Hg0.4Cd0.6 interfaces have shown a significant in-diffusion of the metal overlayer. The influence of shallow In2+ implantation prior to metallization was an increase in pc which occurred above a dose of 1013 ions/cm2. In contrast, Pt and Au formed Schottky barrier diodes on n-type Hg0.4Cd0.6 with øb=0.69eV for Pt and øb=0.79eV for Au. With prior In2+ implantation, both Pt and Au contacts exhibited an ohmic behaviour with pc= 2x10−1 ohm.cm2. These results have significance in the fabrication of devices for 1.0 -2.5μm optical communications.

The Reliability of Multilevel Metallization on InGaAs/GaAs Layers

1994 ◽  
Vol 337 ◽  
Author(s):  
Edward Y. Chang ◽  
J.S. Chen ◽  
J.W. Wu ◽  
K.C. Lin
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Molecular Beam ◽  
Specific Contact Resistance ◽  
Transmission Line Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Specific Contact ◽  
Secondary Ion ◽  
Contact Metal

ABSTRACTNon-alloyed ohmic contacts using Ti/Pt/Au and Ni/Ge/Au on InGaAs/GaAs layers grown by Molecular Beam Epitaxy (MBE) have been investigated. The n-type InGaAs film has a doping concentration higher than 1X1019 cm-3. Specific contact resistance below 2X10-7 Ωcm2 could be easily achieved with Ti/Pt/Au. Due to the layer intermixing and outdiffusion of In and Ga, the specific contact resistance and sheet resistance increase after thermal treatment. When Ni/Ge/Au is used as the contact metal, the outdiffusion of In and Ga atoms is more severe than that of Ti/Pt/Au. After annealing at 450°C for two minutes, the Au4In formed and the characteristics of the contact became worse. All the phenomena illustrated above have been observed and investigated by Transmission Line Model, X-ray diffraction, Auger Electron Spectroscopy and Secondary Ion Mass Spectrum. As far as the thermal stability is concerned, it is convinced that Ti/Pt/Au is the best one of these two non-alloyed ohmic contact studied.

Temperature Behavior of Pt/Au Ohmic Contacts to p-GaN

1997 ◽  
Vol 468 ◽  
Author(s):  
D. J. King ◽  
L. Zhang ◽  
J. C. Ramer ◽  
S. D. Hersee ◽  
L. F. Lester
Keyword(s):  
Contact Resistance ◽  
Room Temperature ◽  
Ohmic Contacts ◽  
Characteristic Curve ◽  
Specific Contact Resistance ◽  
Metal Contacts ◽  
Dopant Activation ◽  
Specific Contact ◽  
Order Of Magnitude ◽  
Increasing Temperature

ABSTRACTOhmic contacts to Mg-doped p-GaN grown by MOCVD [1] are studied using a circular transmission line model (TLM) to avoid the need for isolation. For samples which use a p-dopant activation anneal before metallization, no appreciable difference in the specific contact resistance, rc, as a function of different capping options is observed. However, a lower rc is obtained when no pre-metallization anneal is employed, and the post-metallization anneal simultaneously activates the p-dopant and anneals the contact. This trend is shown for Pt/Au, Pt, Pd/Pt/Au, and Ni/Au contacts to p-GaN. The rc 's for these metal contacts are in the range of 1.4–7.6 × 10-3 ohm-cm2 at room temperature at a bias of 10mA. No particular metallization formula clearly yields a consistently superior contact. Instead, the temperature of the contact has the strongest influence.Detailed studies of the electrical properties of the Pt/Au contacts reveal that the I-V linearity improves significantly with increasing temperature. At room temperature, a slightly rectified I-V characteristic curve is obtained, while at 200°C and above, the I-V curve is linear. For all the p-GaN samples, it is also found that the sheet resistance decreases by an order of magnitude with increasing temperature from 25°C to 350°C. The specific contact resistance is also found to decrease by nearly an order of magnitude for a temperature increase of the same range. A minimum rc of 4.2 × 10-4 ohm-cm2 was obtained at a temperature of 350°C for a Pt/Au contact. This result is the lowest reported rc for ohmic contacts to p-GaN.

Electrical Modelling and Characterisation of Alloyed Ohmic Contacts

1993 ◽  
Vol 318 ◽  
Author(s):  
Geoffrey K. Reeves ◽  
Patrick W. Leech ◽  
H. Barry Harrison
Keyword(s):  
Contact Resistance ◽  
Transmission Line ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Realistic Model ◽  
Specific Contact Resistance ◽  
Transmission Line Model ◽  
Semiconductor Interface ◽  
Line Model ◽  
Specific Contact

ABSTRACTThis paper briefly reviews the standard Transmission Line Model (TLM) commonly used to measure the specific contact resistance of a planar ohmic contact. It is proposed that in the case of a typical Au-Ge-Ni alloyed ohmic contact, a more realistic model would need to take into account the presence of the alloyed layer at the metal-semiconductor interface. An alternative is described which is based on three contact layers and the two interfaces between them, thus forming a Tri-Layer Transmission Line Model (TLTLM). Expressions are given for the contact resistance Rc and the contact end resistance Re of this structure, together with a current division factor, f. Values for the parameters of this model are inferred from experimentally reported values of Rc and Re for two types of contact.

Characteristics of Ti/Pt/Au Ohmic Contacts on p-type GaN/AlxGa1-xN Superlattices

1999 ◽  
Vol 595 ◽  
Author(s):  
L. Zhou ◽  
F. Khan ◽  
A.T. Ping ◽  
A. Osinski ◽  
I. Adesida
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Current Voltage ◽  
Specific Contact ◽  
Superlattice Structures ◽  
P Type

AbstractTi/Pt/Au metallization on p-type GaN/AlxGa1-xN (x=0.10 and 0.20) superlattices (SL) were investigated as ohmic contacts. Current-voltage and specific contact resistance measurements indicate enhanced p-type doping in the superlattice structures compared to that in GaN. Ti/Pt/Au is shown to be an effective ohmic metallization scheme on p-type GaN/AlxGa1-xN superlattices. A specific contact resistance of Rc = 4.6×10-4 Ω-cm2 is achieved for unalloyed Ti/Pt/Au on GaN/Al0.2Ga0.8N SL. This is reduced to 1.3×10-4 Ω-cm2 after annealing for 5 minutes at 300 °C.

scholarly journals Ti/Al Ohmic Contacts to n-Type GaN Nanowires

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Gangfeng Ye ◽  
Kelvin Shi ◽  
Robert Burke ◽  
Joan M. Redwing ◽  
Suzanne E. Mohney
Keyword(s):  
Thermal Stability ◽  
Contact Resistance ◽  
Cross Sections ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Transmission Line Model ◽  
Gan Nanowires ◽  
Transmission Electron ◽  
Titanium Aluminum ◽  
Specific Contact

Titanium/aluminum ohmic contacts to tapered n-type GaN nanowires with triangular cross-sections were studied. To extract the specific contact resistance, the commonly used transmission line model was adapted to the particular nanowire geometry. The most Al-rich composition of the contact provided a low specific contact resistance (mid10−8 Ωcm2) upon annealing at 600 °Cfor 15 s, but it exhibited poor thermal stability due to oxidation of excess elemental Al remaining after annealing, as revealed by transmission electron microscopy. On the other hand, less Al-rich contacts required higher annealing temperatures (850 or 900 °C) to reach a minimum specific contact resistance but exhibited better thermal stability. A spread in the specific contact resistance from contact to contact was tentatively attributed to the different facets that were contacted on the GaN nanowires with a triangular cross-section.

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