Reliability of Ohmic Contacts for AlGaAs/GaAs HBTs

1990 ◽  
Vol 184 ◽  
Author(s):  
G. S. Jackson ◽  
E. Tong ◽  
P. Saledas ◽  
T. E. Kazior ◽  
R. Sprague ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Ion Beam ◽  
Sintering Process ◽  
Electrical Stability ◽  
Long Term Stability ◽  
Heavily Doped ◽  
P Type

ABSTRACTThe reliability of ohmic contacts to thin, heavily doped layers of GaAs is investigated. Pd/Ge/Au contacts to n-type GaAs display excellent electrical stability over extended periods of thermal stress. The contact resistance stays below 0.50Ω-mim during a 2500h, 280°C bake. Reactive ion beam assisted evaporation of Ti with N forms TiN which is introduced as a barrier layer in Pt/TiN/Ti/Au contacts to a thin p+ layer. The TiN layer allows greater process latitude in the sintering process and improves long term stability of the ohmic contact. The microstructure of the p-type contacts is examined with TEM and Auger profiling at different instances of the 2500h, 280°C bake and compared to the contact resistance measurements.

Reliability of Ohmic Contacts for AlGaAs/GaAs HBTs

1990 ◽  
Vol 181 ◽  
Author(s):  
G. S. Jackson ◽  
E. Tong ◽  
P. Saledas ◽  
T. E. Kazior ◽  
R. Sprague ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Ion Beam ◽  
Sintering Process ◽  
Electrical Stability ◽  
Long Term Stability ◽  
Heavily Doped ◽  
P Type

ABSTRACTThe reliability of ohmic contacts to thin, heavily doped layers of GaAs is investigated. Pd/Ge/Au contacts to n-type GaAs display excellent electrical stability over extended periods of thermal stress. The contact resistance stays below 0.5Ω-mm during a 2500h, 280°C bake. Reactive ion beam assisted evaporation of Ti with N forms TiN which is introduced as a barrier layer in Pt/TiN/Ti/Au contacts to a thin p+ layer. The TiN layer allows greater process latitude in the sintering process and improves long term stability of the ohmic contact. The microstructure of the p-type contacts is examined with TEM and Auger profiling at different instances of the 2500h, 280°C bake and compared to the contact resistance measurements.

Pt:Ti Diffusion Barrier, Interconnect, and Simultaneous Ohmic Contacts to n- and p-Type 4H-SiC

2018 ◽  
Vol 924 ◽  
pp. 381-384 ◽  
Author(s):  
Robert S. Okojie ◽  
Dorothy Lukco
Keyword(s):  
Diffusion Barrier ◽  
Ohmic Contacts ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Specific Contact Resistance ◽  
Long Term Stability ◽  
Specific Contact ◽  
P Type ◽  
Fabrication Costs

We report the initial results of using co-sputtered Pt:Ti 80:20 at. % composition ratio metallization as a diffusion barrier against gold (Au) and oxygen (O), as an interconnect layer, as well as forming simultaneous ohmic contacts to n-and p-type 4H-SiC. Having a single conductor with such combined multi-functional attributes would appreciably reduce the fabrication costs, processing time and complexity that are inherent in the production of SiC based devices. Auger Electron Spectroscopy, Focused Ion Beam-assisted Field Emission Scanning Electron Microscopy and Energy Dispersive Spectroscopy analyses revealed no Au and O migration to the SiC contact surface and minimal diffusion through the Pt:Ti barrier layer after 15 minutes of exposure at 800 oC in atmosphere, thus offering potential long term stability of the ohmic contacts. Specific contact resistance values of 7 x 10-5 and 7.4 x 10-4 Ω-cm2 were obtained on the n (Nd=7 x 1018 cm-3) and p (Na=2 x 1020 cm-3) -type 4H-SiC, respectively. The resistivity of 75 μΩ-cm was obtained for the Pt:Ti layer that was sandwiched between two SiO2 layers and annealed in pure O ambient up to 900 °C, which offers promise as a high temperature interconnect metallization.

Titanium Tungsten (TiW) for Ohmic contacts to n-and p-type 4H-SiC

2000 ◽  
Vol 640 ◽  
Author(s):  
S.-K. Lee ◽  
C.-M. Zetterling ◽  
M. Östling
Keyword(s):  
High Temperature ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Term Stability ◽  
Long Term Stability ◽  
Ohmic Behavior ◽  
Specific Contact ◽  
P Type

ABSTRACTIn the present work, we investigated sputtered titanium tungsten (TiW) contacts for Ohmic contacts to both n- and p-type 4H-SiC with long-term stability under high temperature (500°C).. Epitaxial layers with a doping concentration of 1.3×1019 and 6×1018 cm−3 were used. After high temperature annealing (>950°C) sputtered TiW contacts showed Ohmic behavior with good uniform distribution of the specific contact resistance. We obtained an average specific contact resistance (pc) of 4×10−5 Ωcm2 and 1.2 ∼ 1.7×10−4 Ωcm2 for p- and n-type, respectively from linear TLM measurement. We also found some variation of the specific contact resistance and the sheet resistance from our TLM measurement for p-type contacts. We will discuss this behavior with the measurement of SIMS. Long-term stability with a top-cap layer is also discussed

NMR Investigation of the Local Dopant-Hydrogen Configuration in Amorphous Silicon

1987 ◽  
Vol 95 ◽  
Author(s):  
S. E. Ready ◽  
J. B. Boyce
Keyword(s):  
Amorphous Silicon ◽  
Plasma Deposition ◽  
Spin Echo ◽  
Double Resonance ◽  
Structural Units ◽  
Long Term Stability ◽  
Heavily Doped ◽  
P Type ◽  
Hydrogenated Amorphous

AbstractHydrogen's role in the doping efficiency and long term stability of hydrogenated amorphous silicon is not well understood. The introduction of dopants has been observed to cause an increase in the deposition rate and in the formation of dangling bonds. We have performed NMR spin echo double resonance measurements on heavily doped amorphous silicon samples prepared via plasma deposition in order to ascertain the dopanthydrogen structural units. The resulting dopant concentrations were 2.0 and 0.5 at. % boron and/or phosphorus in compensated and singly doped material respectively. Our results indicate no direct dopant-hydrogen bonding in the compensated or n-type samples. However, in the p-type material the data indicate that approximately 40% of the boron atoms are directly bonded to a hydrogen.

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.

Ion beam-treated space polymers: long-term stability in GEO-simulated environments

2021 ◽  
Author(s):  
Jacob Kleiman ◽  
Zelina Iskanderova ◽  
Leonid Krishtein ◽  
J. R. Dennison ◽  
Brian Wood ◽  
...  
Keyword(s):  
Ion Beam ◽  
Term Stability ◽  
Long Term Stability ◽  
Simulated Environments

Ohmic Contacts to GaAs

1982 ◽  
Vol 18 ◽  
Author(s):  
Norman Braslau
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
Spatially Inhomogeneous ◽  
Heavily Doped

The present capability of obtaining ohmic contacts to GaAs over a range of doping levels is reviewed. Possible models of transport across the metalsemiconductor interface are discussed and contact techniques are described. The widely used Au—Ge alloyed contact is seen to have a spatially inhomogeneous interface which appears to control its contact resistance. The most satisfactory process at this time is to alloy into a previously fabricated heavily doped layer.

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 Исследование формирования омических контактов Au/Mo/Ti с пониженным сопротивлением к эпитаксиальным слоям алмаза p-типа

2019 ◽  
Vol 89 (12) ◽  
pp. 1923
Author(s):  
М.Н. Дроздов ◽  
Е.В. Демидов ◽  
Ю.Н. Дроздов ◽  
С.А. Краев ◽  
В.И. Шашкин ◽  
...  
Keyword(s):  
Titanium Carbide ◽  
Contact Resistance ◽  
Ohmic Contacts ◽  
Contact Region ◽  
Effective Diffusion ◽  
Protective Properties ◽  
High Adhesion ◽  
Heavy Doping ◽  
P Type

The formation of ohmic Au/Mo/Ti contacts to epitaxial p-type diamond films is studied. The effect of annealing on the electrical and structural properties of contacts has been investigated. It was shown that during rapid thermal annealing, the outer layer of gold protects the contact system from oxidation up to a temperature of 850°C, unlike the simplified Au/Ti system, which is more common in modern works. In Au/Ti structures without a Mo layer after high-temperature annealing, effective diffusion of titanium into the gold layer occurs, which reduces its protective properties and accelerates the diffusion of oxygen to the boundary with the diamond. Oxidation of the Ti/C contact region blocks the formation of a conductive layer of titanium carbide with high adhesion at the border with diamond. The role of various factors in reducing the contact resistance is compared: annealing for the formation of titanium carbide, heavy doping of diamond with boron atoms, and crystalline perfection of epitaxial diamond substrates. For doped epitaxial films grown on single-sector quality substrates, non-annealed ohmic contacts with a record contact resistance of 4•10<-7> Ω•cm<2> were obtained.

Sign in / Sign up

Export Citation Format

Share Document