Basic Physics of Semiconductors(半导体的基本物理).pdf
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Basic Physics of Semiconductors
* Einstein Relation: Our study of drift and diffusion has introduced a factor for each:
(or ), and (or ), respectively. It can be proved that and are called the
“Einstein Relation”:
Note that: , at 300 K. Figure 1 summarizes the charge transport mechanisms.
Fig.1 Summary of drift and diffusion mechanisms
* PN Junction: We begin our study of semiconductor devices with the junction for three
reasons. (1) The device finds application in many electronic systems, e.g., in adapters that charge
the batteries of cell phones. (2) The pn junction is among the simplest semiconductor devices,
thus providing a good entry point into the study of the operation of such complex structures as
transistors. (3) The pn junction also serves as part of transistors.
In this section, we study the properties and I/V characteristics of pn junctions. The following
outline shows our thought process, indicating that our objective is to develop circuit models that
pn junction see Fig. 2, the p and n sides are called the
can be used in analysis and design. In a “
“anode” and the ”cathode” respectively.
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Fig.2 Outline of concepts to be studied
* PN Junction in Equilibrium
Let us first study the pn junction with no external connections, i.e., the terminals are open and no
voltage is applied across the device. We say the junction is in “equilibrium”. While seemingly of
no practical value
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