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.

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

Improved Low Resistance Contacts of Ni/Au and Pd/Au to P-Type GaN Using a Cryogenic Treatment

1999 ◽  
Vol 595 ◽  
Author(s):  
Mi-Ran Park ◽  
Wayne A. Anderson ◽  
Seong-Ju Park
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Cryogenic Treatment ◽  
Microstructural Analysis ◽  
Chemical Vapor ◽  
Specific Contact Resistance ◽  
Mixed Gas ◽  
Low Resistance ◽  
Specific Contact ◽  
P Type

AbstractA low resistance Ohmic contact to p-type GaN is essential for reliable operation of electronic and optoelectronic devices. Such contacts have been made using Ni/Au and Pd / Au contacts to p-type Mg-doped GaN (1.41×1017 cm−3) grown by metalorganic chemical vapor deposition ( MOCVD ) on ( 0001 ) sapphire substrates. Thermal evaporation was used for the deposition of those metals followed by annealing at temperatures of 400 ∼ 700 °C in an oxygen and nitrogen mixed gas ambient, then subsequently cooled in liquid nitrogen which reduced the specific contact resistance from the range of 9.46∼2.80×10−2 ωcm2 to 9.84∼2.65×10−4 ωcm2 for Ni/Au and from the range of 8.35∼5.01×10−4 ωcm2 to 3.34∼1.80×10−4 ωcm2 for Pd/Au. The electrical characteristics for the contacts were examined by the current versus voltage curves and the specific contact resistance was determined by use of the circular transmission line method (c-TLM). The effects of the cryogenic process on improving Ohmic behavior (I-V linearity) and reducing the specific contact resistance will be discussed from a microstructural analysis which reveals the metallurgy of Ohmic contact formation.

scholarly journals Improved Low Resistance Contacts of Ni/Au and Pd/Au to p-Type GaN Using a Cryogenic Treatment

2000 ◽  
Vol 5 (S1) ◽  
pp. 901-907
Author(s):  
Mi-Ran Park ◽  
Wayne A. Anderson ◽  
Seong-Ju Park
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Cryogenic Treatment ◽  
Microstructural Analysis ◽  
Chemical Vapor ◽  
Specific Contact Resistance ◽  
Mixed Gas ◽  
Low Resistance ◽  
Specific Contact ◽  
P Type

A low resistance Ohmic contact to p-type GaN is essential for reliable operation of electronic and optoelectronic devices. Such contacts have been made using Ni/Au and Pd / Au contacts to p-type Mg-doped GaN (1.41×1017 cm−3) grown by metalorganic chemical vapor deposition ( MOCVD ) on ( 0001 ) sapphire substrates. Thermal evaporation was used for the deposition of those metals followed by annealing at temperatures of 400 ∼ 700 °C in an oxygen and nitrogen mixed gas ambient, then subsequently cooled in liquid nitrogen which reduced the specific contact resistance from the range of 9.46∼2.80×10−2 Ωcm2 to 9.84∼2.65×10−4 Ωcm2 for Ni/Au and from the range of 8.35∼5.01×10−4 Ωcm2 to 3.34∼1.80×10−4 Ωcm2 for Pd/Au. The electrical characteristics for the contacts were examined by the current versus voltage curves and the specific contact resistance was determined by use of the circular transmission line method (c-TLM). The effects of the cryogenic process on improving Ohmic behavior (I-V linearity) and reducing the specific contact resistance will be discussed from a microstructural analysis which reveals the metallurgy of Ohmic contact formation.

Formation of Ni/Pt/Au Ohmic Contacts to p-GaN

1997 ◽  
Vol 482 ◽  
Author(s):  
Ja-Soon Jang ◽  
Hyo-Gun Kim ◽  
Kyung-Hyun Park ◽  
Chang-Sub Um ◽  
Il-Ki Han ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Chemical Vapor ◽  
Electron Beam Evaporation ◽  
Specific Contact Resistance ◽  
Metal Thin Films ◽  
Linear Behavior ◽  
Specific Contact ◽  
P Type

AbstractWe report a new Ni/Pt/Au (20/30/80 nm) metallization scheme to achieve a low ohmic contacts to p-type GaN with a carrier concentration of 9.4 × 1016 cm-3. A Mg-doped GaN layer (0.5 μm) was grown on (0001) sapphire substrate by metalorganic chemical vapor deposition (MOCVD). All metal thin films were deposited on the p-GaN layer in an electron-beam evaporation system. Samples were annealed by a rapid thermal annealing (RTA) process at a range of temperatures from 300 °C to 850 °C under a flowing Ar atmosphere. A circulartransmission line model (c-TLM) was employed to calculate the specific contact resistance, and current-voltage (I-V) data were measured with HP4155A. The Ni/Pt/Au contacts without the annealing process showed nearly rectifying characteristics. The ohmic contacts were formed on the samples annealed at 500 °C for 30 sec and the I-V data showed a linear behavior. The specific contact resistance was 2.1 × 10-2 Ωcm2. However with increasing the annealing temperature above 600 °C, ohmic contacts were again degraded. Auger electron spectroscopy (AES) depth profiles were used to investigate the interfacial reactions between the trilayer and GaN. AES results suggested that Pt plays a significant role in forming ohmic contact as an acceptor at the interface. Atomic force microscope (AFM) also showed that the samples with good ohmic contact have very smooth surface.

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.

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.

On the specific contact resistance of metal contacts to p-type GaN

2006 ◽  
Vol 21 (12) ◽  
pp. 1738-1742 ◽  
Author(s):  
L Lewis ◽  
P P Maaskant ◽  
B Corbett
Keyword(s):  
Contact Resistance ◽  
Specific Contact Resistance ◽  
Metal Contacts ◽  
Specific Contact ◽  
P Type

Effect of Au distribution in NiO/Au film on the ohmic contact formation to p-type GaN

2005 ◽  
Vol 20 (2) ◽  
pp. 456-463 ◽  
Author(s):  
Jiin-Long Yang ◽  
J.S. Chen ◽  
S.J. Chang
Keyword(s):  
Electron Microscopy ◽  
Ohmic Contact ◽  
Incident Angle ◽  
Specific Contact Resistance ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Ohmic Behavior ◽  
Transmission Electron ◽  
Specific Contact ◽  
P Type

The distribution of Au and NiO in NiO/Au ohmic contact on p-type GaN was investigated in this work. Au (5 nm) films were deposited on p-GaN substrates by magnetron sputtering. Some of the Au films were preheated in N2 ambient to agglomerate into semi-connected structure (abbreviated by agg-Au); others were not preheated and remained the continuous (abbreviated by cont-Au). A NiO film (5 nm) was deposited on both types of samples, and all samples were subsequently annealed in N2 ambient at the temperatures ranging from 100 to 500 °C. The surface morphology, phases, and cross-sectional microstructure were investigated by scanning electron microscopy, glancing incident angle x-ray diffraction, and transmission electron microscopy. I-V measurement on the contacts indicates that only the 400 °C annealed NiO/cont-Au/p-GaN sample exhibits ohmic behavior and its specific contact resistance (ρc) is 8.93 × 10−3 Ω cm2. After annealing, Au and NiO contact to GaN individually in the NiO/agg-Au/p-GaN system while the Au and NiO layers become tangled in the NiO/cont-Au/p-GaN system. As a result, the highly tangled NiO-Au structure shall be the key to achieve the ohmic behavior for NiO/cont-Au/p-GaN system.

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.

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