Chapter 24
Transistors
Frequently, I have been asked if an experiment I have planned is pure or applied
research; to me it is more important to know if the experiment will yield new and
probably enduring knowledge about nature. If it is likely to yield such knowledge, it
is, in my opinion, good fundamental research; and this is much more important than
whether the motivation is purely esthetic satisfaction on the part of the experimenter
on the one hand or the improvement of the stability of a high-power transistor on the
other.
W.B. Shockley [2046, 2047]
Abstract The device functionalities of bipolar, heterobipolar and field effect transistors (JFET, MESFET and MOSFET) are explained. Within physical models for drift, diffusion and recombination given
earlier in the book, the characteristics of these devices are derived. Remarks on integrated circuits,
miniaturization and thin film transistors finish this chapter.
24.1 Introduction
Transistors
1 are the key elements for electronic circuits such as amplifiers, memories and microprocessors. Transistors can be realized in bipolar technology (bipolar junction transistor (BJT), Sect. 24.2)
or as unipolar devices using the field effect (field-effect transistor (FET), Sect. 24.3) [574, 2048]. The
equivalent in vacuum-tube technology to the transistor is the triode (Fig. 24.1a). Transistors can be
optimized for their properties in analog circuits such as linearity and frequency response or their properties in digital circuits such as switching speed and power consumption. Transistors for microwave
applications are discussed in [1815]. Early commercial models are shown in Fig. 24.2.
24.2 Bipolar Transistors
Bipolar transistors consist of a pnp or npn sequence (Fig. 24.3). The layers (or parts) are named emitter
(highly doped), base (thin, highly doped) and collector (normal doping level). The transistor can be
considered to consist of two diodes (emitter–base and base–collector) back to back. However, the
1 The term ‘transistor’ was coined from the combination of ‘transconductance’ or ‘transfer’ and ‘varistor’ after initially
such devices were termed ‘semiconductor triodes’. The major breakthrough was achieved in 1947 when the first transistor
was realized that showed gain (Figs. 1.9 and 24.1b).
© Springer Nature Switzerland AG 2021
M. Grundmann, The Physics of Semiconductors, Graduate Texts in Physics,
https://doi.org/10.1007/978-3-030-51569-0_24
691
Transistors
Frequently, I have been asked if an experiment I have planned is pure or applied
research; to me it is more important to know if the experiment will yield new and
probably enduring knowledge about nature. If it is likely to yield such knowledge, it
is, in my opinion, good fundamental research; and this is much more important than
whether the motivation is purely esthetic satisfaction on the part of the experimenter
on the one hand or the improvement of the stability of a high-power transistor on the
other.
W.B. Shockley [2046, 2047]
Abstract The device functionalities of bipolar, heterobipolar and field effect transistors (JFET, MESFET and MOSFET) are explained. Within physical models for drift, diffusion and recombination given
earlier in the book, the characteristics of these devices are derived. Remarks on integrated circuits,
miniaturization and thin film transistors finish this chapter.
24.1 Introduction
Transistors
1 are the key elements for electronic circuits such as amplifiers, memories and microprocessors. Transistors can be realized in bipolar technology (bipolar junction transistor (BJT), Sect. 24.2)
or as unipolar devices using the field effect (field-effect transistor (FET), Sect. 24.3) [574, 2048]. The
equivalent in vacuum-tube technology to the transistor is the triode (Fig. 24.1a). Transistors can be
optimized for their properties in analog circuits such as linearity and frequency response or their properties in digital circuits such as switching speed and power consumption. Transistors for microwave
applications are discussed in [1815]. Early commercial models are shown in Fig. 24.2.
24.2 Bipolar Transistors
Bipolar transistors consist of a pnp or npn sequence (Fig. 24.3). The layers (or parts) are named emitter
(highly doped), base (thin, highly doped) and collector (normal doping level). The transistor can be
considered to consist of two diodes (emitter–base and base–collector) back to back. However, the
1 The term ‘transistor’ was coined from the combination of ‘transconductance’ or ‘transfer’ and ‘varistor’ after initially
such devices were termed ‘semiconductor triodes’. The major breakthrough was achieved in 1947 when the first transistor
was realized that showed gain (Figs. 1.9 and 24.1b).
© Springer Nature Switzerland AG 2021
M. Grundmann, The Physics of Semiconductors, Graduate Texts in Physics,
https://doi.org/10.1007/978-3-030-51569-0_24
691