Preface
Piezoelectric materials may be dielectrics or semiconductors. In piezoelectric semiconductors, the distribution or motion of charge carriers is affected by mechanical
loads through the electric field produced by piezoelectric coupling. Since the 1960s,
there have been efforts on using piezoelectric semiconductors to make acoustic wave
devices where the interaction between mechanical waves and electric currents is
called the acoustoelectric effect. Relatively recently, various piezoelectric semiconductor structures have been synthesized such as ZnO fibers, tubes, belts, spirals, and
films. They have been used to make energy harvesters for converting mechanical
energy into electrical energy, transistors, and various physical as well as chemical
sensors. Piezoelectric semiconductors are also used in nanostructures such as quantum wells, dots, and wires. The study of piezoelectric semiconductor materials and
devices is growing rapidly. The recent studies on the topic have formed new research
areas called piezotronics and piezo-phototronics.
This book is on theoretical analysis of piezoelectric semiconductor structures or
devices using the phenomenological or macroscopic theory. Although most semiconductor books follow a combined microscopic and macroscopic approach, there
exist purely macroscopic semiconductor models with various levels of sophistication. This book employs the simplest drift-diffusion model for semiconduction,
which is electrically coupled to the macroscopic theory of piezoelectricity. This
approach is relatively simple physically. Mathematically, it involves coupled differential equations, ordinary or partial. Of course the phenomenological theory
employed has its limitations, but it can provide some basic understanding of certain
behaviors of piezoelectric semiconductors. In addition to electromechanical couplings, thermal effects such as thermoelastic and pyroelectric couplings are also
discussed. Some equations are repeated in certain sections so that they can be read
independently.
Chapter 1 is a brief summary of the general three-dimensional phenomenological
theory of piezoelectric semiconductors. A few exact solutions of the threedimensional equations are presented in Chap. 2. Then the three-dimensional theory
is reduced to one- and two-dimensional models for the extension of thin rods,
v
Piezoelectric materials may be dielectrics or semiconductors. In piezoelectric semiconductors, the distribution or motion of charge carriers is affected by mechanical
loads through the electric field produced by piezoelectric coupling. Since the 1960s,
there have been efforts on using piezoelectric semiconductors to make acoustic wave
devices where the interaction between mechanical waves and electric currents is
called the acoustoelectric effect. Relatively recently, various piezoelectric semiconductor structures have been synthesized such as ZnO fibers, tubes, belts, spirals, and
films. They have been used to make energy harvesters for converting mechanical
energy into electrical energy, transistors, and various physical as well as chemical
sensors. Piezoelectric semiconductors are also used in nanostructures such as quantum wells, dots, and wires. The study of piezoelectric semiconductor materials and
devices is growing rapidly. The recent studies on the topic have formed new research
areas called piezotronics and piezo-phototronics.
This book is on theoretical analysis of piezoelectric semiconductor structures or
devices using the phenomenological or macroscopic theory. Although most semiconductor books follow a combined microscopic and macroscopic approach, there
exist purely macroscopic semiconductor models with various levels of sophistication. This book employs the simplest drift-diffusion model for semiconduction,
which is electrically coupled to the macroscopic theory of piezoelectricity. This
approach is relatively simple physically. Mathematically, it involves coupled differential equations, ordinary or partial. Of course the phenomenological theory
employed has its limitations, but it can provide some basic understanding of certain
behaviors of piezoelectric semiconductors. In addition to electromechanical couplings, thermal effects such as thermoelastic and pyroelectric couplings are also
discussed. Some equations are repeated in certain sections so that they can be read
independently.
Chapter 1 is a brief summary of the general three-dimensional phenomenological
theory of piezoelectric semiconductors. A few exact solutions of the threedimensional equations are presented in Chap. 2. Then the three-dimensional theory
is reduced to one- and two-dimensional models for the extension of thin rods,
v