Ion Beam Treatment of Ohmic Contacts to n-TYPE Hg1-xCdxTe

1992 ◽  
Vol 260 ◽  
Author(s):  
Patrick W. Leech ◽  
Geoffrey K. Reeves ◽  
Yuan H. Li
Keyword(s):  
Ohmic Contacts ◽  
Rutherford Backscattering Spectrometry ◽  
Ion Beam ◽  
Specific Contact Resistance ◽  
Range Analysis ◽  
Ion Beam Mixing ◽  
Auger Depth Profile ◽  
Specific Contact ◽  
Implantation Techniques ◽  
Ion Beam Treatment

ABSTRACTThe application of ion beam mixing and ion implantation techniques in the formation of ohmic contacts to n-Hg1-xCdxTe (x = 0.6, 0.7) has been investigated. For experiments in ion beam mixing, an indium layer (15nm thick) on Hg1-xCdxTe wasbombarded with 45keV Te+ ions at doses ranging from 1 × 1013 to 1 × 1016 cm2. Minimum values of specific contact resistance, pc, of 4 × 10-4Ωcm-2 were measured for a dose of 1 × 1016 cm-2 after 200°C annealing; pc was independent of dose in this range. Analysis of the interfaces by Auger depth profile and Rutherford backscattering spectrometry has shown that ion beam mixing produced an enhanced indiffusion of indium. In comparison, samples which were ion implanted with In+ at 50keV prior to metalisation showed a reduction in pc which was strongly dependent on dosage.

The Effects of Ion Beam Mixing on Rapid Thermal Annealed Ohmic Contacts to N-GaAs

1990 ◽  
Vol 181 ◽  
Author(s):  
Seemi Kazmi ◽  
Roman V. Kruzelecky ◽  
David A. Thompson
Keyword(s):  
Surface Morphology ◽  
Contact Resistance ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Ohmic Contacts ◽  
Ion Beam ◽  
Depth Profiling ◽  
Specific Contact Resistance ◽  
Ion Beam Mixing ◽  
Specific Contact

ABSTRACTNi/Ge/Au and Ni/Ge/Pd contacts have been made on 1018 cm-3 n-type GaAs. The contacts were subjected to ion beam mixing through the metallization using 70-130 keV Se+ ions and subsequently subjected to rapid thermal annealing (RTA). These are compared with unimplanted contacts produced by RTA techniques on the same substrate. The specific contact resistance ,pc, has been measured for the two systems. In addition, the contacts have been studied using Auger depth profiling and SEM studies have been used to determine surface morphology. Values of pc ∽ 10-6 -10-7 ohm-cm2 have been measured. It is observed that ion beam mixing or the addition of a Ti overlayer (to the Ni/Ge/Au) improves the contact morphology.

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.

The Stability to Ageing of Pd/Zn and Pt-Based Ohmic Contacts to p-InGaAs/InP

1998 ◽  
Vol 514 ◽  
Author(s):  
P. W. Leech ◽  
G. K. Reeves ◽  
P. Ressel
Keyword(s):  
Contact Resistance ◽  
Barrier Layer ◽  
Ohmic Contacts ◽  
Rutherford Backscattering Spectrometry ◽  
Rutherford Backscattering ◽  
Contact System ◽  
Specific Contact Resistance ◽  
Barrier Layers ◽  
Specific Contact ◽  
The Stability

ABSTRACTPd/Zn/Au contacts to p-In0.53Ga0.47As/InP with various barrier layers (Pd, Pt or LaB,) to the indiffusion of Au have been examined by Rutherford Backscattering Spectrometry (RBS). For the metallisations with a barrier layer of Pd, the ageing of the contacts at 400°C for 20 h produced a widespread indiffusion of Au. In comparison, the incorporation of a layer of Pt or amorphous LaB6 prevented an indiffusion of Au and significantly reduced any outdiffusion of the semiconductor elements. The presence of the barrier layer of Pt or LaB6 produced little or no detrimental increase in specific contact resistance, ρc, for this contact system. Values of ρc in the range 8–10 × 10−6 Ω cm2 were obtained for all of the contacts based on Pd/Zn/Au after annealing at 500°C. A comparison has been made with the characteristics of Pt/Ti/Pt/Au contacts to p-In0.53Ga0.47As/ InP which were shown as stable against the indiffusion of Au.

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.

Cobalt Silicide OHMIC Contacts to 6H-SiC

1994 ◽  
Vol 339 ◽  
Author(s):  
Nils Lundberg ◽  
M. Östling
Keyword(s):  
Current Density ◽  
Ohmic Contacts ◽  
Elevated Temperatures ◽  
Rutherford Backscattering Spectrometry ◽  
Temperature Stability ◽  
Specific Contact Resistance ◽  
X Ray Diffraction ◽  
Materials Analysis ◽  
X Ray ◽  
Specific Contact

ABSTRACTMaterials and electrical evaluation were performed to determine the characteristics of ohmic contacts to 6H-SiC. Both elemental metal (Co) and suicides (CoSi and CoSi2) were studied following heat treatments at 500 °C and 900 °C for 5 hours and 2 hours, respectively. Materials analysis by Rutherford Backscattering Spectrometry (RBS) and X-ray Diffraction (XRD) monitored the temperature stability of the contacts after the annealings. Current density-voltage measurements at elevated temperatures established the specific contact resistance pc.

Low Resistance Ohmic Contacts to n-Hg1−xCdxTe Using a HgTe Cap Layer

1994 ◽  
Vol 299 ◽  
Author(s):  
Patrick W. Leech ◽  
Geoffrey K. Reeves
Keyword(s):  
Ohmic Contacts ◽  
Critical Thickness ◽  
Rutherford Backscattering Spectrometry ◽  
Substantial Reduction ◽  
Specific Contact Resistance ◽  
Graded Structure ◽  
Annealing Conditions ◽  
Specific Contact ◽  
Graded Junction

AbstractNon-alloyed ohmic contacts of HgTe on Hg1−xCdxTe (x = 0.60) with metallisations of Ti, In and Au have been investigated. Layers of HgTe with thickness in the range from 0.1 μm to 1.0 μm were grown by organometallic epitaxy either as an abrubt or a graded junction, depending on the in-situ annealing conditions. The layer thickness and the extent of interdiffusion with the Hg1−CdxTe were determined using Rutherford backscattering spectrometry (RBS). The results have shown that an abrupt rather than a graded structure was essential in order to achieve the minimum value of specific contact resistance, ρc, of ≈5 × 10−5 Ωcm2. In addition, a critical thickness of HgTe (≥0.2 μm) was required in order to obtain a substantial reduction in ρc. For these metal/HgTe/Hg1−xCdxTe contacts, the metal Ti has produced the lowest values of ρc and greatest adhesion to the HgTe. Both of these properties have been attributed to the strong interfacial reaction of the overlayer of Ti with HgTe.

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.

Current Transport in Ti/Al/Ni/Au Ohmic Contacts to GaN and AlGaN

2007 ◽  
Vol 556-557 ◽  
pp. 1027-1030 ◽  
Author(s):  
Ferdinando Iucolano ◽  
Fabrizio Roccaforte ◽  
Filippo Giannazzo ◽  
A. Alberti ◽  
Vito Raineri
Keyword(s):  
Contact Resistance ◽  
Field Emission ◽  
Ohmic Contacts ◽  
Theoretical Models ◽  
Specific Contact Resistance ◽  
Strong Increase ◽  
Current Transport ◽  
Electrical Characteristics ◽  
Structural And Electrical Properties ◽  
Specific Contact

In this work, the structural and electrical properties of Ti/Al/Ni/Au contacts on n-type Gallium Nitride were studied. An ohmic behaviour was observed after annealing above 700°C. The structural analysis showed the formation of an interfacial TiN layer and different phases in the reacted layer (AlNi, AlAu4, Al2Au) upon annealing. The temperature dependence of the specific contact resistance demonstrated that the current transport occurs through thermoionic field emission in the contacts annealed at 600°C, and field emission after annealing at higher temperatures. By fitting the data with theoretical models, a reduction of the Schottky barrier from 1.21eV after annealing at 600°C to 0.81eV at 800°C was demonstrated, together with a strong increase of the carrier concentration at the interface. The reduction of the contact resistance upon annealing was discussed by correlating the structural and electrical characteristics of the contacts.

Investigation of Ge, As, and Au Diffusion in Non-Alloyed Epitaxial Au-Ge Ohmic Contacts to n-GaAs Using Secondary Ion Mass Spectroscopy Backside Sputter Depth-Profiling

1991 ◽  
Vol 240 ◽  
Author(s):  
H. S. LEE ◽  
R. T. Lareau ◽  
S. N. Schauer ◽  
R. P. Moerkirk ◽  
K. A. Jones ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
High Concentration ◽  
Ohmic Behavior ◽  
Preferential Sputtering ◽  
Specific Contact ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTA SIMS backside sputter depth-profile technique using marker layers is employed to characterize the diffusion profiles of the Ge, As, and Au in the Au-Ge contacts after annealing at 320 C for various times. This technique overcomes difficulties such as ion beam mixing and preferential sputtering and results in high depth resolution measurements since diffusion profiles are measured from low to high concentration. Localized reactions in the form of islands were observed across the surface of the contact after annealing and were composed of Au, Ge, and As, as determined by SIMS imaging and Auger depth profiling. Backside SIMS profiles indicate both Ge and Au diffusion into the GaAs substrate in the isalnd regions. Ohmic behavior was obtained after a 3 hour anneal with a the lowest average specific contact resistivity found to be ∼ 7 × 100−6 Ω- cm2.

Si+ Implantation and Activation in GaN Comparison of GaN on Sapphire and GaN on Silicon

2012 ◽  
Vol 711 ◽  
pp. 213-217 ◽  
Author(s):  
Anne Elisabeth Bazin ◽  
Frédéric Cayrel ◽  
Mohamed Lamhamdi ◽  
Arnaud Yvon ◽  
Jean Christophe Houdbert ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ohmic Contacts ◽  
Silicon Oxide ◽  
Electrical Activation ◽  
Specific Contact Resistance ◽  
Force Microscopy ◽  
Atomic Force ◽  
Specific Contact ◽  
Good Behaviour ◽  
Scanning Electron

In this paper, we evaluated gallium nitride heteroepitaxially grown on sapphire (GaN/Sa) and grown on silicon (GaN/Si) faced to implantation doping. Si+ was implanted on low doped n-type epilayers in order to create a plateau around 1020at.cm-3. All the samples were capped with a silicon oxide and annealed between 1000°C and 1150°C. The surface quality was evaluated in terms of roughness, pit density and maximum pit diameter using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Finally, the dopant electrical activation was studied with Ti-Al contacts using the circular Transfert Length Method (c-TLM). This study shows that low Specific Contact Resistance (SCR) values of 8x10-5Ω.cm2 and 6x10-6Ω.cm2 are respectively obtained on GaN/Sa sample annealed at 1150°C-2min and on GaN/Si sample annealed at 1150°C-30s, proving that good ohmic contacts are obtained on both materials. Nevertheless, a compromise has to be done between the low SCR values obtained and the GaN surface degradation, observed by AFM and SEM after the different annealing treatments and which could affect the good behaviour of the GaN devices.

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