Thermal Stability for Reflectance and Specific Contact Resistance of Ni/Ag-Based Contacts on p-Type GaN

2009 ◽  
Vol 12 (9) ◽  
pp. H315 ◽  
Author(s):  
Ray-Ming Lin ◽  
Yi-Lun Chou ◽  
Wan-Ching Tseng ◽  
Chia-Lung Tsai ◽  
Jen-Chih Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Contact Resistance ◽  
Specific Contact Resistance ◽  
Specific Contact ◽  
P Type

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.

Thermal Stability in Pd-Based Contacts to p-Type In0.53Ga0.47as Characterized by Rbs

1995 ◽  
Vol 406 ◽  
Author(s):  
P. W. Leech ◽  
P. Ressel ◽  
G. K. Reeves ◽  
W. Zhou ◽  
E. Kuphal
Keyword(s):  
Thermal Stability ◽  
Contact Resistance ◽  
Ohmic Contact ◽  
Specific Contact Resistance ◽  
Specific Contact ◽  
P Type ◽  
Zn Ions ◽  
Interfacial Characteristics ◽  
Structural Layer

AbstractThe resistivity and interfacial characteristics of Pd/Zn/Pd/Au and Pd/Zn/Au/LaBd6/Au contacts to p-In0.53Ga0.47As have been investigated. Annealing of the contacts at 375–425°C yielded a minimum in specific contact resistance, p,, of 2 × 10-7 Δ cm2 for the Pd/Zn/Pd/Au contacts and 1 Δ cm2 for the Pd/Zn/Au/LaB6/Au configuration. This is the lowest reported measurement of pc for an ohmic contact to p-In0.53Ga0.47As doped to ≤1 × 1019 cm−3. In the Pd/Zn/Au/LaB6/Au scheme, the minimum in pc was the same irrespective of whether the Zn was incorporated as a structural layer or as Zn ions implanted into the interfacial Pd prior to metallization. The effect of thickness of the Zn layer on pc has been determined for the Pd/Zn/Au/LaB6/Au scheme. RBS measurements have shown that during annealing, the LaB6 layer acted as a barrier to the indiffusion of Au and to the degradation of the In0.53Ga0.47As substrate.

Improvement of the Specific Contact Resistance on P-Type 4H-SiC by Using a Highly P-Typed Doped 4H-SiC Layer Selectively Grown by VLS Transport

2014 ◽  
Vol 806 ◽  
pp. 57-60
Author(s):  
Nicolas Thierry-Jebali ◽  
Arthur Vo-Ha ◽  
Davy Carole ◽  
Mihai Lazar ◽  
Gabriel Ferro ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Schottky Barrier Height ◽  
Annealing Temperature ◽  
Process Condition ◽  
Specific Contact Resistance ◽  
High Doping Level ◽  
Annealing Temperatures ◽  
Specific Contact ◽  
P Type

This work reports on the improvement of ohmic contacts made on heavily p-type doped 4H-SiC epitaxial layer selectively grown by Vapor-Liquid-Solid (VLS) transport. Even before any annealing process, the contact is ohmic. This behavior can be explained by the high doping level of the VLS layer (Al concentration > 1020 cm-3) as characterized by SIMS profiling. Upon variation of annealing temperatures, a minimum value of the Specific Contact Resistance (SCR) down to 1.3x10-6 Ω.cm2 has been obtained for both 500 °C and 800 °C annealing temperature. However, a large variation of the SCR was observed for a same process condition. This variation is mainly attributed to a variation of the Schottky Barrier Height.

Ohmic Contacts to p-Type InGaAs/InP with a Graded Bandgap Heterobarrier

1993 ◽  
Vol 318 ◽  
Author(s):  
Patrick W. Leech ◽  
Geoffrey K. Reeves
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Rutherford Backscattering Spectrometry ◽  
Specific Contact Resistance ◽  
Superlattice Structure ◽  
Specific Contact ◽  
P Type ◽  
Metal Layers ◽  
Anneal Temperature ◽  
Graded Bandgap

ABSTRACTOhmic contacts to p-type InP with an In0.47Ga0.53As buffer layer and an interposed superlattice of 50 Å In0.47Ga0.53As/ 50 Å InP have been investigated. Initial studies of contacts to In0.47Ga0.53As/ InP without the superlattice structure have shown that Pd/Zn/Pd/Au metallization produced a lower specific contact resistance (pc = 1.1 × 10−4 Ω cm2) than Pd/Ge/Au, and over a wider range of anneal temperature than Au/Zn/Au. The incorporation of the superlattice in the p-In0.47Ga0.53As/ InP structure resulted in Pd/Zn/Pd/Au contacts with pc of 3.2 × 10−5 Ω cm2 as-deposited and 7.5 × 10−6 Ω.cm2 after a 500 °C anneal. The presence of Pd/Zn in the metallization was shown as important in reducing pc. Significant intermixing of the metal layers and In0.47Ga0.53As occured at ≥ 350 °C, as revealed by Rutherford backscattering spectrometry.

scholarly journals Behavior of W and WSix Contact Metallization on n- and p- Type GaN

1999 ◽  
Vol 4 (S1) ◽  
pp. 684-690
Author(s):  
X. A. Cao ◽  
F. Ren ◽  
J. R. Lothian ◽  
S. J. Pearton ◽  
C. R. Abernathy ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Annealing Temperature ◽  
Specific Contact Resistance ◽  
Ohmic Behavior ◽  
Contact Metallization ◽  
Specific Contact ◽  
Heavily Doped ◽  
Sputter Deposited ◽  
Optimum Annealing Temperature ◽  
P Type

Sputter-deposited W-based contacts on p-GaN (NA∼1018 cm−3) display non-ohmic behavior independent of annealing temperature when measured at 25°C. The transition to ohmic behavior occurs above ∼250°C as more of the acceptors become ionized. The optimum annealing temperature is ∼700°C under these conditions. These contacts are much more thermally stable than the conventional Ni/Au metallization, which shows a severely degraded morphology even at 700°C. W-based contacts may be ohmic as-deposited on very heavily doped n-GaN, and the specific contact resistance improves with annealing up to ∼900°C.

Ni-Al-Ti Ohmic Contacts with Preserved Form Factor and Few 10- 4 Ωcm2 Specific Resistance on 0.1-1 Ωcm p-Type 4H-SiC

2018 ◽  
Vol 924 ◽  
pp. 385-388 ◽  
Author(s):  
Roberta Nipoti ◽  
Maurizio Puzzanghera ◽  
Maria Concetta Canino ◽  
Giovanna Sozzi ◽  
Paolo Fedeli
Keyword(s):  
Form Factor ◽  
Contact Resistance ◽  
Contact Area ◽  
Room Temperature ◽  
Ohmic Contacts ◽  
Specific Resistance ◽  
Thickness Ratio ◽  
Specific Contact Resistance ◽  
Specific Contact ◽  
P Type

This study shows that a thin Ni film on Al/Ti/4H-SiC metal pads allows to preserve the pad form factor during a 1000 °C/2 min treatment, provided that the Al and Ti film thicknesses are sufficiently thin. Moreover, by reducing the Al to Ti thickness ratio, droplet formation in the contact area is avoided and a mirror-like appearance is obtained. This optimal contact morphology corresponds to a specific contact resistance of few 10-4Ωcm2at room temperature on p-type 4H-SiC with resistivity in the range 0.1 – 1 Ωcm.

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 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.

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