Junction

Schematic band structure for (a) metal (b) insulator, (c) semiconductor (d) N-type semiconductor (e) Atype semiconductor (0 P-N semiconductor junction. uppermost band shown is called the conduction band because once electrons access its levels, they are essentially free to conduct electricity. Metals have high conductivity because the conduction band contains electrons from the outset. One has to imagine that there are a mind-boggling 1022 electrons per cubic centimeter ( one per...

57 Amorphous Thin Films

Systems, Structures, and Transformations Amorphous or glassy materials have a structure that exhibits only short-range order or regions where a predictable placement of atoms occurs. However, within a very few atom spacings, this order breaks down, and no long-range correlation in the geometric positioning of atoms is preserved. Although bulk amorphous materials such as silica glasses, slags, and polymers are well known, amorphous metals were originally not thought to exist. An...

72 Structural Aspects of Epitaxial Films

Prior to consideration of epitaxial films, it is instructive to examine the nature of the topmost surface layers of a crystalline solid film. The reason the surface will generally have different properties than the interior of the film can be understood by a schematic cross-sectional view as shown in Fig. 7-3. If the surface structure is the predictable extension of the underlying lattice, we have the case shown in Fig. 7-3a. The loss of periodicity in one direction will tend to alter surface...

Info

Au-Selected Semiconductors and Chalcogenides 3. Au-Selected Semiconductors and Chalcogenides CaC03 (3) MgO (20) Mica (23) Al203 (sapphire) (2) Si02 (quartz) (4) BaTiO, (2) ZnO (2) Numbers of references dealing with particular All substrate-' system are in parentheses. recent compilation (Ref. 14), and yet they correspond to over 300 references to the research literature. Other epitaxial metal film-substrate systems have been comprehensively tabulated (Ref. 15) together with deposition methods...

46 CVD Processes and Systems

The great variety of materials deposited by CVD methods has inspired the design and construction of an equally large number of processes and systems. These have been broadly categorized and described by such terms as low and high temperature, atmospheric and low pressure, cold and hot wall, closed and open in order to differentiate them. Incorporation of physical deposition features such as plasmas and evaporation sources has further enriched and expanded the number of potential CVD processes....

54 Cluster Coalescence and Depletion

Island is 7, so the total energy Gy Airrf 7. The island contains a number of atoms n, given by 4irr,3 3i2, where Q is the atomic volume. Defining the free energy per atom as dGy dni in this application, we have, after substitution, Making use of Eq. 1-9 0 + kT In a,), we see that the Gibbs-Thomson relation directly follows. This equation states that atoms in an island of radius r can be in equilibrium only with a substrate adatom activity or effective concentration a,. The quantity ax may be...

Electrical and Magnetic Properties of Thin Films

Thin Film Resistivity

Introduction to Electrical Properties of Thin Films Electrical properties of thin films have long been of practical importance and theoretical interest. The solid-state revolution has created important new roles for thin film electrical conductors, insulators, and devices. What was once accomplished with large discrete electrical components and systems is now more efficiently and reliably achieved with microscopic thin-film-based integrated circuit chips. Regardless of the class of...

85 Metal Semiconductor Reactions

Junction Spiking

All semiconductor devices and integrated circuits require contacts to connect them to other devices and components. When a metal contacts a semiconductor surface, two types of electrical behavior can be distinguished in response to an applied voltage. In the first type, the contact behaves like a P-N junction and rectifies current. The ohmic contact, on the other hand, passes current equally as a function of voltage polarity. In Section 10.4 the electrical properties of metal-semiconductor...

1000

Note E epitaxial P polycrystalline A amorphous. Adapted from Refs. 1, 2, 3. Note E epitaxial P polycrystalline A amorphous. Adapted from Refs. 1, 2, 3. Deposition reactions at substrates include 2GaCl + As2 + H 2 < * 2GaAs + 2HC1, 2GaCl + P2 + H 2 ** 2GaP + 2HC1, 2InCl + P2 + H2 2InP + 2HC1, 2InCl + As2 + H2 ** 2InAs + 2HC1. (4-16) Aspects of the properties of these deposited films will be discussed in Chapter 7. The previous examples are but a small sample of the total number of film and...

0exp ad 1 7[expai l

Where J0 primary electron current density from external source a number of ions per unit length produced by electrons 7 number of secondary electrons emitted per incident ion d interelectrode spacing. a. If the film deposition rate during sputtering is proportional to the product of J and S, calculate the proportionality constant for Cu in this system if the deposition rate is 200 A min for 0.5-keV Ar ions. Assume a 0.1 ion cm, y 0.08 electron ion, d 10 cm, and J0 100 mA cm2. b. What deposition...

23 Vacuum Pumps and Systems

Pump Moving Parts

The vacuum systems employed to deposit and characterize thin films contain an assortment of pumps, tubing, valves, and gauges to establish and measure the required reduced pressures (Ref. 7). Of these components pumps are generally the most important, and only they will be discussed at any length. Vacuum pumps may be divided into two broad categories gas transfer pumps and entrapment pumps. Gas transfer pumps remove gas molecules from the pumped volume and convey them to the ambient in one or...

73 Lattice Misfit and Imperfections in Epitaxial Films

Molten Metal Atomization

In this section we explore some implications of lattice misfit on the perfection of epitaxial films. The basic theory that accounts for the elastic-plastic changes in the bilayer was introduced by Frank and van der Merwe (Ref. 4). It attempts to account for the accommodation of misfit between two lattices rather than being a theory of epitaxy per se. The theory predicts that any epitaxial layer having a lattice parameter mismatch with the substrate of less than 9 would grow pseudomorphically...

Handbook Of Crystal Growth Thin Films Au Insb Diagram

Application of ion bombardment is the enhancement of the density and index of refraction of optical coatings. This subject is treated again in Chapter 11. 3.8.4. Ionized Cluster Beam (ICB) Deposition (Ref. 33) The idea of employing energetic ionized clusters of atoms to deposit thin films is due to T. Takagi. In this novel technique, vapor-phase aggregates or clusters, thought to contain a few hundred to a few thousand atoms, are Figure 3-26. Schematic diagram of ICB system. (Courtesy of W. L....

34 Evaporation Hardware and Techniques

Post Tensioned Anchorage Systems

Resistance-Heated Evaporation Sources This section will primarily be devoted to a brief description of the most widely used methods for heating vaporants. Clearly, heaters must reach the tempera ture of the vaporant in question while having a negligible vapor pressure in comparison. Ideally, they should not contaminate, react, or alloy with the vaporant or release gases such as oxygen, nitrogen, or hydrogen at the evaporation temperature. These requirements have led to the development...

Stopping Power Of Thin Films

Na vapor lamp, 536 Nanoindenter, 412-413, 564 Narrow band filter, 540 NbN, 675 N el wall 494 energy, 495 Nernst-Einstein equation, 39, 356, 435 electromigration, 383 Neutral filter, 538 Ni, 598, 601 CVD, 149 implanted in stainless steel, 615 Ni-Si. 391 Ni-Zr, 236 TEM micrograph, 239 Ni2Si, 391 NiAl, 581 NiSi, 391 NiSi2, 391 Nitrides, 551 alloy, 558 Nitriding, 580-581 Nonabsorbing film, 524, 526 Nuclear stopping power, 611 Nucleation, 40, 195, 200, 202 atomistic theory, 206 charge effects, 218...

Rotary Mechanical Pump

Schematic of vacuum deposition system. high 10 10 torr vacuum deposition and surface analytical equipment, but are being supplanted by turbomolecular and cryopumps. The broad variety of applications requiring a low-pressure environment is reflected in a corresponding diversity of vacuum system design. One such system shown in Fig. 2-12 is employed for vacuum evaporation of metals. The basic pumping system consists of a nominal 15-cm diameter, multistage oil-diffusion pump backed by...

Milton Ohring

Stevens Institute of Technology Department of Materials Science and Engineering Hoboken, New Jersey Academic Press San Diego New York Boston London Sydney Tokyo Toronto This book is printed on acid-free paper. 5 Copyright 1992 by Academic Press All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from...

Review of Materials Science

A cursory consideration of the vast body of solid substances reveals what outwardly appears to be an endless multitude of external forms and structures possessing a bewildering variety of properties. The branch of study known as materials science and engineering evolved in part to classify those features that are common among the structure and properties of different materials in a manner somewhat reminiscent of chemical or biological classification schemes. This dramatically reduces the...