Development of Electrode Materials for Semiconductor Devices

2005 ◽  
Vol 475-479 ◽  
pp. 1705-1714
Author(s):  
Masanori Murakami ◽  
Yasuo Koide ◽  
Miki Moriyama ◽  
Susumu Tsukimoto
Keyword(s):  
Ohmic Contact ◽  
High Speed ◽  
Electrode Materials ◽  
Chemical Vapor ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Organic Chemical ◽  
Contact Materials ◽  
Low Resistance ◽  
Metal Organic

Recent strong demands for optoelectronic communication and portable telephones have encouraged engineers to develop optoelectronic devices, microwave devices, and high-speed devices using heterostructural compound semiconductors. Although the compound crystal growth techniques had reached at a level to control the compositional stoichiometry and crystal defects on a nearly atomic scale by the advanced techniques such as molecular beam epitaxy and metal organic chemical vapor deposition techniques, development of ohmic contact materials (which play a key role to inject external electric current from the metals to the semiconductors) was still on a trial-and-error basis. Our research efforts have been focused to develop, low resistance, refractory ohmic contact materials using the deposition and annealing techniques for n-GaAs, p-ZnSe, InP, p-SiC p-CdTe etc. It was found the growth of homo- or hetero–epitaxial intermediate semiconductor layers (ISL) was essential for low resistance contact formation. The importance of hetero-structural ISL was given taking an example of n-type ohmic contact for GaAs.

Atomic Scale Aluminum and Strain Distribution in a Gan/AlxGa1−XN Heterostructure

1997 ◽  
Vol 482 ◽  
Author(s):  
Christian Kisielowski ◽  
Olaf Schmidt ◽  
Jinwei Yang
Keyword(s):  
Three Dimensional ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Organic Chemical ◽  
Well Test ◽  
Lattice Constants ◽  
Resolution Electron ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

AbstractA GaN/AlxGalxN multi-quantum well test structure with Al concentrations 0 ≤ xAl ≤ 1 was utilized to investigate the growth of AlxGal–xN barrier layers deposited by metal organic chemical vapor deposition (MOCVD). A transition from a two dimensional (2D) to a three dimensional (3D) growth mode was observed in AlxGa1–xN barriers with XAl ≥ 0.75. It is argued that the transition occurs because of growth at temperatures that are low compared with the materials melting points Tmelt. The resulting rough AlxGa1–xN surfaces can be planarized by overgrowth with GaN. Quantitative high resolution electron microscopy (HREM) was applied to measure composition and strain profiles across the GaN/AlxGa1−xN stacks at an atomic level. The measurements reveal a substantial variation of lattice constants at the AlxGa1−xN/GaN interfaces that is attributed to an Al accumulation.

Multifunctional oxide nanostructures by metal-organic chemical vapor deposition (MOCVD)

2009 ◽  
Vol 81 (8) ◽  
pp. 1523-1534 ◽  
Author(s):  
François Weiss ◽  
Marc Audier ◽  
Ausrine Bartasyte ◽  
Daniel Bellet ◽  
Cécile Girardot ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Atomic Scale ◽  
Perovskite Oxide ◽  
Organic Chemical ◽  
Oxide Materials ◽  
Oxide Nanostructures ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

The development of thin films, in the context of ongoing reduction in the size of electronic systems, poses challenging questions for the materials sciences of multifunctional nanostructures. These include the limits of size reduction, integration of heterogeneous functions, and system characterization or process control at an atomic scale. We present here different studies devoted to perovskite oxide materials (or materials with derived structure), where in specific directions of the crystal structure the atomic organization decreases down to a few nanometers, thus building nanostructures. In these materials, very original physical phenomena are observed in multilayers or superlattices, nanowires (NWs) or nanodots, mainly because strain, surfaces, and interfaces play here a predominant role and can tune the physical properties. Metal-organic chemical vapor deposition (MOCVD) routes have been used for the synthesis of oxide materials. We first introduce the basic rules governing the choice of metal-organic precursors for the MOCVD reaction. Next we discuss the principles of the pulsed injection MOCVD system. A laser-assisted MOCVD system, designed to the direct growth of 2D and 3D photonic structures, will also be described. Selected case studies will finally be presented, illustrating the powerful development of different oxide nanostructures based on dielectric, ferroelectric, or superconducting oxides, manganites, and nickelates, as well as first results related to the growth of ZnO NWs.

scholarly journals Ab initio molecular dynamics of atomic-scale surface reactions: insights into metal organic chemical vapor deposition of AlN on graphene

2018 ◽  
Vol 20 (26) ◽  
pp. 17751-17761 ◽  
Author(s):  
D. G. Sangiovanni ◽  
G. K. Gueorguiev ◽  
A. Kakanakova-Georgieva
Keyword(s):  
Molecular Dynamics ◽  
Density Functional ◽  
Surface Reactions ◽  
Chemical Vapor ◽  
Atomic Scale ◽  
Ab Initio Molecular Dynamics ◽  
Organic Chemical ◽  
Pristine Graphene ◽  
Metal Organic ◽  
Dynamics Simulations

Density-functional molecular dynamics simulations provide plausible interpretations of atomistic and electronic processes responsible for delivery of Al, C adatoms, and C–Al, CHx, AlNH2 admolecules on pristine graphene via precursor/surface reactions.

In‐situ growth of yba2cu3o7‐x films by metal organic chemical vapor deposition using vertical, high‐speed rotating disk reactor.

1989 ◽  
Vol 169 ◽  
Author(s):  
D. W. Noh ◽  
B. Gallois ◽  
Y. Q. Li ◽  
C. Chern ◽  
B. Rear ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
High Speed ◽  
Chemical Vapor ◽  
Rotating Disk ◽  
Organic Chemical ◽  
Axis Orientation ◽  
Rotating Disk Reactor ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition

AbstractSuperconducting thin films of YBa2Cu307‐x were grown on MgO (100) and YSZ(IOO) substrates without post‐annealing by metal organic chemical vapor deposition using vertical, high‐speed (1100 rpm) rotating disk reactor. The source materials were Y(tmhd)3, Ba(tmhd)2, and Cu(tmhd)2, which were kept at 135 °C, 240 °C, and 120 °C respectively. The precursors were transported using nitrogen as the carrier gas and introduced separately into the cylindrical stainless steel reaction chamber, which was maintained at 60 torr. The oxygen partial pressure was 30 Torr. The substrates were heated resistively at 800°C. After growth, the films were cooled down at a rate of 5 °C/min under 1 atmospheric pressure of pure oxygen. The X‐ray diffraction pattern of the films showed primarily an orientation of c‐axis perpendicular to the substrates, with weak peaks of (hoo) corresponding to a‐axis orientation. Scanning Electron Microscopy of the films showed a well‐developed a‐axis and c‐axis plate‐like structure which appeared as rectangular micron‐sized features on the MgO surface. On the YSZ substrates a‐axis and c‐axis plate‐like projections were also observed, with the dense plate‐like c‐axis orientation dominant. Four probe resistance measurements showed Tc(R=0) at 91.8 K(△TC=2.2 K) and 85 K (△TC=7 K) on YSZ and MgO substrates respectively.

Improving contact performance of graphene on p-type GaN thin films with V-pits microstructures

2018 ◽  
Vol 32 (19) ◽  
pp. 1840052
Author(s):  
Ruo-Nong Song ◽  
Wen-Cheng Ke
Keyword(s):  
Thin Films ◽  
Ohmic Contact ◽  
Carrier Transport ◽  
Single Layer ◽  
Chemical Vapor ◽  
Single Layer Graphene ◽  
Visible Range ◽  
Organic Chemical ◽  
Metal Organic ◽  
P Type

This study presents the electrical properties of graphene that directly is contact on two types of p-type GaN thin films. The diameter of several hundred nanometer V-pits were formed on the p-GaN thin films by adjusting the NH3 flow rate during the metal organic chemical vapor deposition epitaxial process. The single-layer graphene with a high transmittance of 97% in the visible range was transferred on p-GaN thin films to form an Ohmic contact. The V-pits provide more carrier transport paths that promote the carrier tunneling into p-GaN thin films, resulting in a better Ohmic contact performance. In addition, the increased current value was attributed to the presence of V-pits on the p-GaN thin films.

Structural and electronic properties of defects in semiconductors

1995 ◽  
Vol 53 ◽  
pp. 4-5
Author(s):  
J.L. Batstone
Keyword(s):  
Semiconductor Device ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Extended Defects ◽  
Transmission Electron ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Metal Organic ◽  
Film Substrate

The development of growth techniques such as metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy during the last fifteen years has resulted in the growth of high quality epitaxial semiconductor thin films for the semiconductor device industry. The III-V and II-VI semiconductors exhibit a wide range of fundamental band gap energies, enabling the fabrication of sophisticated optoelectronic devices such as lasers and electroluminescent displays. However, the radiative efficiency of such devices is strongly affected by the presence of optically and electrically active defects within the epitaxial layer; thus an understanding of factors influencing the defect densities is required.Extended defects such as dislocations, twins, stacking faults and grain boundaries can occur during epitaxial growth to relieve the misfit strain that builds up. Such defects can nucleate either at surfaces or thin film/substrate interfaces and the growth and nucleation events can be determined by in situ transmission electron microscopy (TEM).

Sign in / Sign up

Export Citation Format

Share Document