19
2
Review of Basic Device Physics
2.1 Introduction
Compact device models for circuit CAD (computer-aided design) requires
detailed description of the transistor characteristics in the circuit environment
under various biasing conditions. Transistor characteristics, however, depend
on the material properties of the basic building blocks of each transistor along
with its geometrical and structural information. IC (integrated circuit) transistors are fabricated on a semiconductor substrate such as silicon to achieve the
desired device characteristics for the target circuit performance. These device
characteristics are modulated by the transport of current-carrying fundamental constituents of matter referred to as the electrons and holes. Again, the electronic properties of semiconductors, primarily, depend on the transport of the
majority carrier electrons or holes. The semiconductors with the majority carrier concentration as electrons are referred to as the n-type, whereas, the semiconductors with the majority carrier concentration as holes are referred to as
the p-type. Thus, in order to understand the compact device models for circuit
CAD, it is essential to understand the basic physics of the elemental n-type, and
p-type semiconductors along with the transport properties of electrons and
holes in building IC devices. Though a number of published titles are available on the subject, the objective of this chapter is to present a brief overview
of the basic semiconductor theory along with the basics of n-type and p-type
semiconductors in contact forming pn-junctions that are necessary to develop
compact transistor models for circuit CAD. The review is brief and covers only
those topics that have direct relevance to the field-effect transistor ICs. For more
exclusive treatments, the readers are referred to textbooks on the subject [1–13].
2.2 Semiconductor Physics
Crystalline silicon is a widely used semiconductor-starting material in the
fabrication of IC devices and chips. Thus, unless otherwise specified, in
this book, the semiconductor physics is described with reference to silicon.
2
Review of Basic Device Physics
2.1 Introduction
Compact device models for circuit CAD (computer-aided design) requires
detailed description of the transistor characteristics in the circuit environment
under various biasing conditions. Transistor characteristics, however, depend
on the material properties of the basic building blocks of each transistor along
with its geometrical and structural information. IC (integrated circuit) transistors are fabricated on a semiconductor substrate such as silicon to achieve the
desired device characteristics for the target circuit performance. These device
characteristics are modulated by the transport of current-carrying fundamental constituents of matter referred to as the electrons and holes. Again, the electronic properties of semiconductors, primarily, depend on the transport of the
majority carrier electrons or holes. The semiconductors with the majority carrier concentration as electrons are referred to as the n-type, whereas, the semiconductors with the majority carrier concentration as holes are referred to as
the p-type. Thus, in order to understand the compact device models for circuit
CAD, it is essential to understand the basic physics of the elemental n-type, and
p-type semiconductors along with the transport properties of electrons and
holes in building IC devices. Though a number of published titles are available on the subject, the objective of this chapter is to present a brief overview
of the basic semiconductor theory along with the basics of n-type and p-type
semiconductors in contact forming pn-junctions that are necessary to develop
compact transistor models for circuit CAD. The review is brief and covers only
those topics that have direct relevance to the field-effect transistor ICs. For more
exclusive treatments, the readers are referred to textbooks on the subject [1–13].
2.2 Semiconductor Physics
Crystalline silicon is a widely used semiconductor-starting material in the
fabrication of IC devices and chips. Thus, unless otherwise specified, in
this book, the semiconductor physics is described with reference to silicon.