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Matlab电子电路分析（第三卷） . M3 |7 @& h1 p; }& x" }
CHAPTER TEN " w2 F" D. [/ H0 U8 a0 z% t3 d
SEMICONDUCTOR PHYSICS
/ s5 N# G" C7 R/ u2 g8 Q" `In 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& I# C" h; G+ U2 L8 L
ductors are discussed. The characteristics of depletion and diffusion capaci[size=9.96001pt]tance are explored through the use of example problems solved with4 d5 @" A( a5 l R! |9 J
MATLAB. The effect of doping concentration on the breakdown voltage of[size=9.96001pt]pn junctions is examined.% @* K: ~8 m, N. t
10.1 INTRINSIC SEMICONDUCTORS + y9 d/ Y$ X0 q1 l6 d8 j! ^
10.1.1 Energy bands
q' \" k7 B; P1 O8 ^2 XAccording 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! j& l: M v! B- u& J
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/ B; |3 R% H6 [" i% ?6 V3 ], j
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& i, a, K! a; D4 ^4 V
a direct band gap semiconductor. # q2 N$ u% K: D1 l0 T5 m
The 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 energy8 P. `4 P9 K( Y! o' Y7 ]) w
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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' H9 t! X; N! P' o0 D2 S[size=9.96001pt]1 \8 `) V4 a, G* t8 C: H& d
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发表于 2020-5-19 10:40
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