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Matlab电子电路分析（第三卷） + _ T9 J( T4 K* g$ V8 F' c& w
CHAPTER TEN ' E0 d X( i: x1 x; F0 j3 Q
SEMICONDUCTOR PHYSICS 6 s2 U* ?# ^2 _' C- w
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 semicon2 n5 {7 p; N3 r( T, ?! w
ductors are discussed. The characteristics of depletion and diffusion capaci[size=9.96001pt]tance are explored through the use of example problems solved with9 N. w! _1 n( |+ }- c. a: d
MATLAB. The effect of doping concentration on the breakdown voltage of[size=9.96001pt]pn junctions is examined.+ [! G( J3 C- s0 {
10.1 INTRINSIC SEMICONDUCTORS
0 @- q" U1 j7 _+ q( U10.1.1 Energy bands/ ^3 k3 c2 i7 I
According 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
+ y/ A+ j/ {, l' r5 B/ ~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 the8 `. U9 `1 B" ^' u: o$ Y" D7 k
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
* J, B2 Z1 U. t- r- [" Ca direct band gap semiconductor. 8 |' Q& j- V( {( }' W
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 energy* c! u6 m! C" E) U4 A5 ]
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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- O: o7 i1 F) }[size=9.96001pt]4 Z9 f/ B# Q& Q" T8 o+ k7 o
) X8 t# a1 [3 f( V7 c, `' W( x! g$ t6 O
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发表于 2020-5-19 10:40
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