Behavior of Zinc During Formation of Au(Zn) Ohmic Contacts to P-Type GaAs

1993 ◽  
Vol 300 ◽  
Author(s):  
E. Kamińska ◽  
A. Piotrowska ◽  
E. Mizera ◽  
R. Zarecka ◽  
J. Adamczewska ◽  
...  
Keyword(s):  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Native Oxide ◽  
Significant Feature ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
Contact Metallization ◽  
Transmission Electron ◽  
P Type

ABSTRACTThe reactions between (100) GaAs and Au, Zn, and Au(Zn) ohmic contact metallization have been investigated by the use of transmission electron microscopy and x-ray diffraction. Emphasis is placed on the particular role of Zn during consecutive stages of the formation of an ohmic contact to p-GaAs. The most significant feature of the interaction of Zn with GaAs is the penetration of Zn atoms into the native oxide, which remains at the surface of GaAs after chemical treatment. Moreover, the presence of Zn in Au-based metallization is found to considerably suppress the thermally induced growth of metallization grains, making the microstructure of the contact virtually intact upon annealing at temperatures up to 460°C.

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.

A structural analysis of the Pd/GaN ohmic contact annealing behavior

2002 ◽  
Vol 743 ◽  
Author(s):  
C. C. Kim ◽  
P. Ruterana ◽  
J. H. Je
Keyword(s):  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Structural Evolution ◽  
Electron Beam Evaporation ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Annealing Behavior ◽  
X Ray ◽  
Transmission Electron ◽  
The Relationship

AbstractFor ohmic contact on p GaN, palladium is one of the best candidates showing ohmic characteristics already without annealing. To be realized in devices, it is necessary to know the behavior of the ohmic contacts at accelerated conditions, especially for high temperatures and power. We report on the structural evolution of palladium layers (30 nm) deposited on GaN (0001) by electron beam evaporation without intentional annealing. They were next cut into various pieces which were individually submitted to rapid thermal annealing at 400, 500, 600, 700 and 800°C for 10 sec. We investigate the differences in the microstructure and the location of interfacial phases and their relationships as determined by X-ray diffraction and transmission electron microscopy, we then suggest the formation mechanism based on the relationship. It is shown that the interface is disrupted at annealing above 600°C and by 800°C only very small patches of Pd are still present, however they area completely imbedded in a matrix of intermetallic phases (gallides) formed by the reaction with GaN.

Investigation of TiW Contacts to 4H-SiC Bipolar Junction Devices

2006 ◽  
Vol 527-529 ◽  
pp. 887-890
Author(s):  
Hyung Seok Lee ◽  
Martin Domeij ◽  
Carl Mikael Zetterling ◽  
Mikael Östling ◽  
Jun Lu
Keyword(s):  
Ohmic Contacts ◽  
Carbide Formation ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Transmission Line Method ◽  
Before And After ◽  
Different Temperatures ◽  
Important Challenge ◽  
Junction Transistor ◽  
P Type

One important challenge in SiC Bipolar Junction Transistor (BJT) fabrication is to form good ohmic contacts to both n-type and p-type SiC. In this paper, we have examined contact study in a SiC BJT process with sputter deposition of titanium tungsten contacts to both n-type and p-type regions followed by annealing at different temperatures between 750 oC and 950 oC. The contacts were characterized using linear transmission line method (LTLM) structures. To see the formation of compound phases, X-ray Diffraction (XRD) θ-2θ scans were performed before and after annealing. The results indicate that 5 minutes annealing at 950 oC of the n+ contact is sufficient whereas the p+ contacts remain non-ohmic after 30 minutes annealing. The n+ emitter structure contact resistivity after 5 min annealing with 750 oC and 950 oC was 1.08 × 10-3 5cm2 and 4.08 × 10-4 5cm2, respectively. Small amorphous regions of silicon and carbon as well as titanium tungsten carbide regions were observed by high-resolution transmission electron microscopy (HRTEM), whereas less carbide formation and no amorphous regions were found in a sample with unsuccessful formation of TiW ohmic contacts.

Ohmic Contacts on p-Type SiC Using Al/C Films

2006 ◽  
Vol 527-529 ◽  
pp. 899-902 ◽  
Author(s):  
Wei Jie Lu ◽  
G.R. Landis ◽  
W.E. Collins ◽  
W.C. Mitchel
Keyword(s):  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Control Sample ◽  
Alloy Film ◽  
Single Component ◽  
X Ray Diffraction ◽  
Contact Formation ◽  
Interfacial Structures ◽  
P Type ◽  
Ohmic Contact Formation

Al based alloys, such as Ti/Al, are commonly used for ohmic contacts on p-type SiC. The interfacial structures of a metal alloy film on SiC are very complicated after annealing. Al is considered as the key element responsible for forming ohmic contacts on p-type SiC, and reacts with C from SiC and forms Al4C3 and Si during annealing. In this study, we have investigated ohmic contact formation of a single component Al4C3 film on p-type SiC. Based on the stoichiometric formation of Al4C3 between Al and C at high temperatures, several samples with various Al/C mole ratios have been examined for ohmic contact formation after different annealing temperatures. Carbon rich and stoichiometric Al4C3 films form ohmic contacts on p-type 4H-SiC (~2.8 x1018 cm-3 ) after annealing at 800 and 900°C. X-ray diffraction (XRD) data have shown that a single component Al4C3 is formed when an ohmic contact on p-type SiC is activated. Al/SiC, as the control sample, does not form ohmic contacts under the same conditions. This study reveals that Al4C3 can be responsible for forming ohmic contacts on p-type SiC. However, its chemical instability requires that the secondary metal is necessary to form stable ohmic contacts when Albased films are used.

Ohmic Contact to n-GaN with TiN Diffusion Barrier

1996 ◽  
Vol 449 ◽  
Author(s):  
E. Kamińska ◽  
A. Piotrowska ◽  
M. Guziewicz ◽  
S. Kasjaniuk ◽  
A. Barcz ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Ohmic Contact ◽  
Diffusion Barrier ◽  
Ohmic Contacts ◽  
Diffusion Barriers ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
Thermally Induced ◽  
X Ray ◽  
Tin Diffusion Barrier

ABSTRACTThe formation of n-GaN/Ti ohmic contacts with TiN diffusion barriers has been investigated by electrical measurements, x-ray diffraction and SIMS. It has been shown that the onset of the ohmic behaviour is associated with the thermally induced phase transformation of Ti into TiN at the GaN/Ti interface. It is suggested that the process is accompanied by an increase in the doping level in the semiconductor subcontact region. The presence of a TiN barrier is found to inhibit excessive decomposition of GaN and to confine the reaction between n-GaN and Ti.

AlxGa1-xN-Based Materials and Heterostructures

1996 ◽  
Vol 449 ◽  
Author(s):  
P. Kung ◽  
A. Saxler ◽  
D. Walker ◽  
X. Zhang ◽  
R. Lavado ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Bragg Reflectors ◽  
X Ray Diffraction ◽  
Chemical Vapor Deposition Growth ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Dimensional Electron Gas ◽  
P Type

ABSTRACTWe present the metalorganic chemical vapor deposition growth, n-type and p-type doping and characterization of AlxGa1-xN alloys on sapphire substrates. We report the fabrication of Bragg reflectors and the demonstration of two dimensional electron gas structures using AlxGa1-xN high quality films. We report the structural characterization of the AlxGa1-xN / GaN multilayer structures and superlattices through X-ray diffraction and transmission electron microscopy. A density of screw and mixed threading dislocations as low as 107 cm-2 was estimated in AlxGa1-xN / GaN structures. The realization of AlxGa1-xN based UV photodetectors with tailored cut-off wavelengths from 365 to 200 nm are presented.

The Microstructure and Electrical Properties of Directly Deposited TiN Ohmic Contacts to Gallium Nitride.

1999 ◽  
Vol 595 ◽  
Author(s):  
P. Ruterana ◽  
G. Nouet ◽  
Th. Kehagias ◽  
Ph. Komninou ◽  
Th. Karakostas ◽  
...  
Keyword(s):  
Gallium Nitride ◽  
Electrical Properties ◽  
Film Thickness ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Epitaxial Relationship ◽  
Si Doped ◽  
P Type ◽  
20 Nm

AbstractWhen the stoichiometric TiN was deposited directly on GaN, we obtained columnar TiN grains of 5-20 nm section which cross the whole film thickness and are rotated mostly around the [111] axis. The conventional epitaxial relationship is obtained and no amorphous patches are observed at the interface. The deposition of TiN on Si doped GaN layers lead to the formation of an ohmic contact, whereas we obtain a rectifying contact on p type layers.

scholarly journals Role of Surfactants in the Properties of Poly(Ethylene Terephthalate)/Purified Clay Nanocomposites

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1397 ◽  
Author(s):  
Elaine dos Santos ◽  
Marcus Fook ◽  
Oscar Malta ◽  
Suédina de Lima Silva ◽  
Itamara Leite
Keyword(s):  
Clay Nanocomposites ◽  
Phosphonium Salts ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Alkyl Ammonium ◽  
Pet Crystallization

Purified clay was modified with different amounts of alkyl ammonium and phosphonium salts and used as filler in the preparation of PET nanocomposites via melt intercalation. The effect of this type of filler on morphology and thermal and mechanical properties of PET nanocomposites was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analyses (TG), tensile properties, and transmission electron microscopy (TEM). The results showed that the mixture of alkyl ammonium and phosphonium salts favored the production of PET nanocomposites with intercalated and partially exfoliated morphologies with slight improvement in thermal stability. In addition, the incorporation of these organoclays tended to inhibit PET crystallization behavior, which is profitable in the production of transparent bottles.

Thermal quenching behavior of Er-doped silicon-rich SiO2 prepared by ion implantation

2004 ◽  
Vol 19 (9) ◽  
pp. 2699-2702 ◽  
Author(s):  
C.S. Zhang ◽  
H.B Xiao ◽  
Y.J. Wang ◽  
Z.J. Chen ◽  
X.L. Cheng ◽  
...  
Keyword(s):  
Silicon Nanocrystals ◽  
Annealing Temperature ◽  
Thermal Quenching ◽  
X Ray Diffraction ◽  
X Ray ◽  
Radiative Processes ◽  
Transmission Electron ◽  
Weak Intensity ◽  
Er Doped

Erbium and silicon were dual implanted into thermally grown SiO2 film on Si (110) substrates, followed by thermal treatment at 700–1200 °C for 30 min. The microstructure was studied by transmission electron microscope and x-ray diffraction. When the implanted films were annealed at T > 900 °C, the silicon nanocrystals (nc-Si) enwrapped by amorphous silicon (a-Si) could be observed. The thermal quenching behavior at λ = 1.535 μm and its relation with the annealling temperature were also investigated. With increasing annealing temperature, the portion of a-Si and the thermal quenching both decreased. Efficient luminescence from Er ions and weak intensity thermal quenching were obtained from the sample annealed at 1100 °C. The role of a-Si in non-radiative processes at T > 100 K is discussed.

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.

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