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Matlab电子电路分析（第三卷） / U P) p3 \; }/ H4 \! o
CHAPTER TEN
3 S R7 g( X U9 d, ]8 ZSEMICONDUCTOR PHYSICS
/ e8 D5 W1 G# h$ ?: H: aIn this chapter, a brief description of the basic concepts governing the flow of [size=9.96001pt]current in a pn junction are discussed. Both intrinsic and extrinsic semicon
' I5 ~0 u( N" M3 r9 e8 Z# zductors are discussed. The characteristics of depletion and diffusion capaci[size=9.96001pt]tance are explored through the use of example problems solved with- l8 \/ u* @! C7 n: r2 ?- }7 I
MATLAB. The effect of doping concentration on the breakdown voltage of[size=9.96001pt]pn junctions is examined.
: U+ o+ E6 q0 P/ P10.1 INTRINSIC SEMICONDUCTORS
3 q. K! Y3 p- D; j! p10.1.1 Energy bands
: w# V6 s: h# I* G5 ^ sAccording to the planetary model of an isolated atom, the nucleus that con[size=9.96001pt]tains protons and neutrons constitutes most of the mass of the atom. Electrons( s% F$ n, S5 E3 G3 |
surround the nucleus in specific orbits. The electrons are negatively charged[size=9.96001pt]and the nucleus is positively charged. If an electron absorbs energy (in the' M# d& G+ j0 Y
form of a photon), it moves to orbits further from the nucleus. An electron[size=9.96001pt]transition from a higher energy orbit to a lower energy orbit emits a photon for/ S! G5 h) \3 ^ z4 Y# @+ W, C4 n
a direct band gap semiconductor.
. G; H# F5 `# @) v% BThe energy levels of the outer electrons form energy bands. In insulators, the[size=9.96001pt]lower energy band (valence band) is completely filled and the next energy
1 |9 u9 O, i+ Y. q5 C# b0 \2 ?band (conduction band) is completely empty. The valence and conduction[size=9.96001pt]bands are separated by a forbidden energy gap.
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7 z$ d, P. ^/ O4 B8 N3 H+ ?* P[size=9.96001pt]
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发表于 2020-5-19 10:40
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