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.

Nonalloyed Ohmic Contacts to N-Si Using a Strained Si0.5Ge0.5 Buffer Layer

1993 ◽  
Vol 320 ◽  
Author(s):  
Hsing-Kuen Liou ◽  
Edward S. Yang ◽  
K. N. Tu
Keyword(s):  
Buffer Layer ◽  
Photoelectron Spectroscopy ◽  
Ohmic Contacts ◽  
Depth Profiling ◽  
Binding Energies ◽  
Specific Contact Resistance ◽  
Strained Si ◽  
X Ray ◽  
Ohmic Behavior ◽  
Specific Contact

ABSTRACTNonalloyed shallow ohmic contacts to n-Si have been fabricated by using an 80 Å thick strained Si0.5Ge0.5 buffer layer grown by molecular beam epitaxy. X-ray photoelectron spectroscopy was employed to investigate the Si 2p and Ge 3d core level binding energies of the strained and the relaxed Si0.5Ge0.5 and to determine their relative Fermi level positions. It was found that the surfaces of strained Si0.5Ge0.5 exhibit pinning very close to the conduction band. Rutherford backscattering and Auger depth profiling were employed to determine the contact reactions using Ti, W or Pt as contact metals. In the case of Pt, a 500 Å W diffusion barrier can protect the ohmic behavior up to 550 °C for 30 min. The specific contact resistance of the Pt/W/Si0.5Ge0.5/n-Si contact extracted from the D-type cross-bridge Kelvin resistor was 3.5x10-5 Ω·cm2.

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.

Atomic force microscopy (AFM) of the topography of silicon surfaces exposed to ion beams

1992 ◽  
Vol 50 (2) ◽  
pp. 1132-1133
Author(s):  
Mark Denker ◽  
Jennifer Wall ◽  
Mark Ray ◽  
Richard Linton
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Incidence Angle ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Ion Beams ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Trace Impurities ◽  
Energy Dose

Reactive ion beams such as O2+ and Cs+ are used in Secondary Ion Mass Spectrometry (SIMS) to analyze solids for trace impurities. Primary beam properties such as energy, dose, and incidence angle can be systematically varied to optimize depth resolution versus sensitivity tradeoffs for a given SIMS depth profiling application. However, it is generally observed that the sputtering process causes surface roughening, typically represented by nanometer-sized features such as cones, pits, pyramids, and ripples. A roughened surface will degrade the depth resolution of the SIMS data. The purpose of this study is to examine the relationship of the roughness of the surface to the primary ion beam energy, dose, and incidence angle. AFM offers the ability to quantitatively probe this surface roughness. For the initial investigations, the sample chosen was <100> silicon, and the ion beam was O2+.Work to date by other researchers typically employed Scanning Tunneling Microscopy (STM) to probe the surface topography.

scholarly journals Ion Beam Analysis for the Investigation of Diffusion Processes

2020 ◽  
Vol 13 ◽  
pp. 51
Author(s):  
H.-W. Becker
Keyword(s):  
Diffusion Processes ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Ion Beam Analysis ◽  
Beam Analysis ◽  
Diffusion Studies ◽  
New Applications ◽  
Diffusion Of Hydrogen ◽  
High Depth

The unique advantages of ion beam analysis, such as the depth resolved unam- biguous stoichometric information of RBS or the possibility to detect hydrogen with high depth resolution still opens new applications in fundamental as well as applied science. Two examples are presented here.The diffusion of hydrogen in cement during the formation of cement has been studied with the 15N hydrogen depth profiling. It could be shown, that the known stages of the hydration process are correlated with the diffusion of hydrogen on a nanometer scale.Diffusion processes play also an important role in geology. The investigation of such processes with RBS will be presented. Prospects of diffusion studies using isotopie tracing with low lying resonances will be discussed.

scholarly journals Time-Of-Flight ERDA for Depth Profiling of Light Elements

2020 ◽  
Vol 4 (4) ◽  
pp. 40
Author(s):  
Keisuke Yasuda
Keyword(s):  
Ion Beam ◽  
Time Of Flight ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Semiconductor Detectors ◽  
Light Elements ◽  
Elastic Recoil ◽  
Measurement Sensitivity ◽  
Elastic Recoil Detection ◽  
Detection Analysis

The time-of-flight elastic recoil detection analysis (TOF-ERDA) method is one of the ion beam analysis methods that is capable of analyzing light elements in a sample with excellent depth resolution. In this method, simultaneous measurements of recoil ion energy and time of flight are performed, and ion mass is evaluated. The energy of recoil ions is calculated from TOF, which gives better energy resolution than conventional Silicon semiconductor detectors (SSDs). TOF-ERDA is expected to be particularly applicable for the analysis of light elements in thin films. In this review, the principle of TOF-ERDA measurement and details of the measurement equipment along with the performance of the instrumentation, including depth resolution and measurement sensitivity, are described. Examples of TOF-ERDA analysis are presented with a focus on the results obtained from the measurement system developed by the author.

Current Transport Mechanisms in Au-Free Metallizations for CMOS Compatible GaN HEMT Technology

2020 ◽  
Vol 1004 ◽  
pp. 725-730
Author(s):  
Fabrizio Roccaforte ◽  
Monia Spera ◽  
Salvatore Di Franco ◽  
Raffaella Lo Nigro ◽  
Patrick Fiorenza ◽  
...  
Keyword(s):  
Barrier Height ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Current Transport ◽  
Large Area ◽  
Si Substrates ◽  
Ohmic Behavior ◽  
Specific Contact ◽  
Thermionic Field Emission

Gallium nitride (GaN) and its AlGaN/GaN heterostructures grown on large area Si substrates are promising systems to fabricate power devices inside the existing Si CMOS lines. For this purpose, however, Au-free metallizations are required to avoid cross contaminations. In this paper, the mechanisms of current transport in Au-free metallization on AlGaN/GaN heterostructures are studied, with a focus on non-recessed Ti/Al/Ti Ohmic contacts. In particular, an Ohmic behavior of Ti/Al/Ti stacks was observed after an annealing at moderate temperature (600°C). The values of the specific contact resistance ρc decreased from 1.6×104 Ω.cm2 to 7×105 Ω.cm2 with increasing the annealing time from 60 to 180s. The temperature dependence of ρc indicated that the current flow is ruled by a thermionic field emission (TFE) mechanism, with barrier height values of 0.58 eV and 0.52 eV, respectively. Finally, preliminary results on the forward and reverse bias characterization of Au-free tungsten carbide (WC) Schottky contacts are presented. This contact exhibited a barrier height value of 0.82 eV.

Characterization of Surfaces and Thin Films by Means of an Ion Microprobe Analyzer

1986 ◽  
Vol 75 ◽  
Author(s):  
Eiichi Izumi ◽  
Yoshinori Ikebe ◽  
Hiroyasu Shichi ◽  
Hifumi Tamura
Keyword(s):  
Thin Films ◽  
Depth Profile ◽  
Ion Beam ◽  
Depth Resolution ◽  
Negative Ion ◽  
Plastic Film ◽  
Ion Microprobe ◽  
Monitoring Method ◽  
Secondary Ion

A variety of materials such as semiconductors, metals, and insulators have been analyzed by use of the Hitachi IMA-3 ion microprobe analyzer. From the depth profile of a GaAs/AQ GaAs superlattice(50Å), a depth resolution of 45Å was obtained at 2350Å below the surface. The stable depth profile of a multilayer plastic film was obtained by using the negative ion beam(O) as a primary ion for charge neutralization. Further, the usefulness of the total ion monitoring method for correcting the changing factors of secondary ion intensity is demonstrated.

Investigation of Cu-Ge/Gaas Metal-Semiconductor Interfaces for Low Resistance Ohmic Contacts

1996 ◽  
Vol 448 ◽  
Author(s):  
Serge Oktyabrsky ◽  
M.A. Borek ◽  
M.O. Aboelfotoh ◽  
J. Narayan
Keyword(s):  
Interfacial Layer ◽  
Ohmic Contacts ◽  
High Thermal Stability ◽  
Contact Resistivity ◽  
Polycrystalline Layer ◽  
Ohmic Behavior ◽  
Semiconductor Interfaces ◽  
Transmission Electron ◽  
Specific Contact ◽  
Specific Contact Resistivity

AbstractChemistry and interfacial reactions of the Cu-Ge alloyed ohmic contacts to n-GaAs with extremely low specific contact resistivity (6.5×10-7 Ω·cm2 for n~1017 cm-3) have been investigated by transmission electron microscopy, EDX and SIMS. Unique properties of the contact layers are related to the formation (at Ge concentration above 15 at.%) of a polycrystalline layer of ordered orthorhombic ε1-Cu3Ge phase. Formation of the ε1-phase is believed to be responsible for high thermal stability, interface sharpness and uniform chemical composition. The results suggest that the formation of the ζ- and ε1,-Cu3Ge phases creates a highly Ge-doped n+-GaAs interfacial layer which provides the low contact resistivity. Layers with Ge deficiency to form ζ-phase show nonuniform intermediate layer of hexagonal β-Cu3As phase which grows epitaxially on Ga{111} planes of GaAs. In this case, released Ga diffuses out and dissolves in the alloyed layer stabilizing the ζ-phase which is formed in the structures with average Ge concentration of as low as 5 at.%. These layers also exhibit ohmic behavior.

Electroless Nickel for N-Type Contact on 4H-SiC

2012 ◽  
Vol 717-720 ◽  
pp. 837-840 ◽  
Author(s):  
Suwan P. Mendis ◽  
Chin Che Tin ◽  
Michelle T. Tin ◽  
Tamara Isaacs-Smith ◽  
Erika R. Crandall
Keyword(s):  
Surface Science ◽  
Ohmic Contacts ◽  
Electroless Nickel ◽  
Electroless Nickel Plating ◽  
Electrical Measurements ◽  
High Concentration ◽  
Broad Area ◽  
Specific Contact ◽  
Type Contact ◽  
Ohmic Contact Formation

An electroless nickel film contains 5-14% by weight of phosphorus. Because of the presence of such a high concentration of phosphorus, electroless nickel can be a useful and convenient source of phosphorus dopant in the fabrication of n-type ohmic contacts for SiC. This paper describes the successful deposition of a Ni:P layer on 4H-SiC through electroless nickel plating followed by a discussion of the results of surface science and electrical measurements. Specific contact resistivity on lightly-doped samples with carrier concentration of 2.5 ´ 1016 cm-3 has been found to be about 4.8 ´ 10-6 Ωcm2 without any need for ion implantation. This metallization technique is especially useful in broad area ohmic contact formation on the back of n-type SiC substrate.

Backside Sims Study Of Ge/Pd Non-Alloyed Ohmic Contacts On InGaAs

1994 ◽  
Vol 354 ◽  
Author(s):  
S.A. Schwarz ◽  
C.J. Pahnstrom ◽  
R. Bhat ◽  
M. Koza ◽  
L.C. Wang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Secondary Ion Mass Spectrometry ◽  
Layer Structure ◽  
Depth Profiling ◽  
Surface Region ◽  
Marker Layer ◽  
Ion Mass Spectrometry ◽  
Secondary Ion

AbstractBackside secondary ion mass spectrometry (SIMS) is employed to examine the Ge/Pd non-alloyed ohmic contact on InGaAs. 130 nm Ge/ 50 nm Pd contacts were deposited on an InP/InGaAs marker layer structure. The contacts were annealed for various times at 200°C and 325°C. Samples were mechanically and chemically thinned to facilitate sputter profiling from the backside, thereby avoiding problems such as roughening or non-uniformity of the metallic layers. Subsequent to depth profiling, additional anneals were performed on the thinned samples, and the samples were reexamined. Extensive reaction of Pd with InGaAs is observed on deposition. Little additional reaction occurs at 200°C. At 325°C, Pd is reclaimed from the reacted surface region, forming PdGe with some excess Ge at the interface. In-diffiision of Pd and Ge into InGaAs is observed at longer annealing times. The results are contrasted with prior studies on GaAs, InP, and InGaAs.

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