2 MEMS and NEMS Foundations
No one behind, no one ahead. The path the ancients
cleared has closed. And the other path, everyone’s
path, easy and wide, goes nowhere. I am alone and
find my way.
Dharmakirti
(7th century India)
Introduction
Chapter 1 Historical Note: The Ascent of Si,
MEMS, and NEMS
Chapter 2 Crystallography
Chapter 3 Quantum Mechanics and the Band
Theory of Solids
Chapter 4 Silicon Single Crystal Is Still King
Chapter 5 Photonics
Chapter 6 Fluidics
Chapter 7 Electrochemical and Optical Analyti-
cal Techniques
Introduction
In Volume I, we lay the foundations for a qualitative
and quantitative understanding of micro- and nano-
electromechanical systems, i.e., MEMS and NEMS.
In integrated circuits (ICs), MEMS, and NEMS, sili-
con (Si) is still the substrate and building material
of choice. A historical note about the history of the
ascent of silicon, MEMS, and NEMS is the topic
ofChapter 1.
The necessary solid-state physics background of
electronic, mechanical, and optical properties of
solids relied on in MEMS and NEMS is covered in
Chapters 2–5. Solid-state physics is the study of sol-
ids. A major part of solid-state physics is focused on
crystals because the periodicity of atoms in a crys-
tal facilitates mathematical modeling, but more
importantly because crystalline materials often
have electrical, optical, or mechanical properties
that can be easier exploited for engineering pur-
poses. In Chapter 2, we detail crystalline materi-
als in which atoms are arranged in a pattern that
repeats periodically in three dimensions. The mate-
rials covered here prepare the reader for Chapter
3, which explains the band theory of solids based
on quantum mechanics. The relevance of quantum
mechanics in the context of ICs and NEMS can-
not be underestimated, and the profound implica-
tions of quantum physics for nanoelectronics and
NEMS is a recurring topic throughout this book.
This is followed in Chapter 4 by a description of
the single-crystal Si band structure, the growth of
single crystals of Si, its doping, and oxidation. In
this chapter, we also review the single-crystal Si
properties that conspired to make Si so important
in electronic, optical, and mechanical devices so
that one might rightly call the second half of the
20th century the Silicon Age. Although the empha-
sis in this book is on nonelectronic applications
of miniaturized devices, we briefly introduce dif-
ferent types of diodes and two types of transistors
(bipolar and MOSFET). In Chapter 5, we introduce
photonics. We compare electron and photon propa-
gation in materials and contrast electron and pho-
tonic confinement structures and the associated
evanescent wave phenomena. We also delve into
the fascinating new topic of metamaterials, artifi-
cially engineered materials possessing properties
(e.g., optical, electrical) that are not encountered in
naturally occurring ones. An introduction to diode
lasers, quantum well lasers, and quantum cascade
lasers concludes the photonics section.
Fluidics and electrochemical and optical analyti-
cal techniques are important current applications
of MEMS and NEMS. In Chapter 6 we introduce
fluidics, compare various fluidic propulsion mech-
anisms, and discuss the influence of miniaturiza-
tion on fluidbehavior. Given the current academic
and industrial interest, fluidics in miniaturized
analytical equipment is detailed separately at the
end of this chapter. Chapter 7 combines a treatise on
STM image showing standing waves in a 2D electron gas
trapped in a “quantum corral” made by positioning Fe
atoms on a Cu (111) surface.
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