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.

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.

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.

scholarly journals Highly Conductive Nanocrystalline Diamond Films and Electronic Metallization Scheme

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4484
Author(s):  
Xin Chen ◽  
Markus Mohr ◽  
Kai Brühne ◽  
Hans-Jörg Fecht
Keyword(s):  
Contact Resistance ◽  
Electron Affinity ◽  
Diamond Films ◽  
Nanocrystalline Diamond ◽  
Etching Process ◽  
Diamond Surface ◽  
Specific Contact Resistance ◽  
Ion Etching ◽  
Nanocrystalline Diamond Films ◽  
Specific Contact

By using a methane and hydrogen process gas mixture in an appropriate hot-filament CVD process without further dopant, high electrical conductivity of over 100 S/cm has been achieved in nanocrystalline diamond films deposited on silicon single-crystalline substrates. Furthermore, it was found that an oxygen reactive-ion etching process (O-RIE) can improve the diamond film surface’s electron affinity, thus reducing the specific contact resistance. The reduction of the specific contact resistance by a factor of up to 16 was realized by the oxygen ion etching process, down to 6×10−6 Ωcm2 We provide a qualitative explanation for the mechanism behind the contact resistance reduction in terms of the electron affinity of the diamond surface. With the aid of XPS, AFM, and surface wetting measurements, we confirmed that a higher surface electron affinity is responsible for the lower specific contact resistance of the oxygen-terminated nanocrystalline diamond films.

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.

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.

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

2000 ◽  
Vol 5 (S1) ◽  
pp. 514-520
Author(s):  
L. Zhou ◽  
F. Khan ◽  
A.T. Ping ◽  
A. Osinsk ◽  
I. Adesida
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Current Voltage ◽  
Specific Contact ◽  
Superlattice Structures ◽  
P Type

Ti/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.

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