Chapter 21
Diodes
Abstract A thorough treatment of Schottky (metal-semiconductor) diodes, MIS (metal-insulatorsemiconductor) diodes and (bipolar) pn-diodes is given, focussing on suitable materials, the formation
of space charge layers and the forward and reverse current-voltage characteristics. Applications of such
devices based on their rectifying properties are discussed.
21.1 Introduction
One of the simplest
1 semiconductor devices is the diode. It is a so-called two-terminal device, i.e. a
device with two leads. The most prominent property of a diode is the rectifying current-voltage (I –V )
characteristic. This function was initially realized with vacuum tubes (Fig. 21.1); a heated filament
emits electrons that are transferred through vacuum to the anode if it is on a positive potential. The
semiconductor diode technology led to a tremendous miniaturization, integration with other devices
(in planar technology) and cost reduction.
We distinguish
2 unipolar diodes, for which the majority carriers cause the effects (e.g. metalsemiconductor diodes), and bipolar diodes in which minority carriers play the decisive role, e.g. in the
pn junction diode.
(a)
(b)
(c)
Fig. 21.1 a Schematic image of a vacuum diode. The electron current flows from the heated cathode to the anode when
the latter is at a positive potential. b One of John A. Fleming’s first diode ‘valves’, 1904. c Commercial ‘tungar’ rectifier,
around 1916 [1679] (b, c). Adapted from [1678]
1 The simplest device is a resistor made from a homogeneous piece of semiconductor, used, e.g., as a part of an integrated
circuit or as a photoresistor as discussed in Sect. 22.2.
2 This distinction is not only made for diodes but also many other semiconductor devices such as transistors, see Chap. 24.
© 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_21
517
Diodes
Abstract A thorough treatment of Schottky (metal-semiconductor) diodes, MIS (metal-insulatorsemiconductor) diodes and (bipolar) pn-diodes is given, focussing on suitable materials, the formation
of space charge layers and the forward and reverse current-voltage characteristics. Applications of such
devices based on their rectifying properties are discussed.
21.1 Introduction
One of the simplest
1 semiconductor devices is the diode. It is a so-called two-terminal device, i.e. a
device with two leads. The most prominent property of a diode is the rectifying current-voltage (I –V )
characteristic. This function was initially realized with vacuum tubes (Fig. 21.1); a heated filament
emits electrons that are transferred through vacuum to the anode if it is on a positive potential. The
semiconductor diode technology led to a tremendous miniaturization, integration with other devices
(in planar technology) and cost reduction.
We distinguish
2 unipolar diodes, for which the majority carriers cause the effects (e.g. metalsemiconductor diodes), and bipolar diodes in which minority carriers play the decisive role, e.g. in the
pn junction diode.
(a)
(b)
(c)
Fig. 21.1 a Schematic image of a vacuum diode. The electron current flows from the heated cathode to the anode when
the latter is at a positive potential. b One of John A. Fleming’s first diode ‘valves’, 1904. c Commercial ‘tungar’ rectifier,
around 1916 [1679] (b, c). Adapted from [1678]
1 The simplest device is a resistor made from a homogeneous piece of semiconductor, used, e.g., as a part of an integrated
circuit or as a photoresistor as discussed in Sect. 22.2.
2 This distinction is not only made for diodes but also many other semiconductor devices such as transistors, see Chap. 24.
© 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_21
517