Transcript 半導體元件及其原理介紹

半導體物理 (三)
半導體元件及其原理介紹
半導體元件及其原理介紹
• The p-n junction in equilibrium
• Current flow in a forward-biased p-n junction
• Current flow in a reverse-biased p-n junction
• Junction geometry and depletion layer capacitance
• Semiconductor heterojunctions
• Metal-semiconductor junctions
• The quantum well and superlattice
The p-n junction in equilibrium
 Ec p  E Fp 
n p  N c exp 

kT 

 Ecn  E Fn 
nn  N c exp 

kT


E Fp  E Fn  E F
 nn 
Ec p  Ecn  kT ln   eV0
n 
 p
kT  nn 
V0 
ln
e  n p 
nn  N d
pp  Na
np  ni2
kT  N d N a 
V0 
ln 2 
e  ni 
  eV0 
n p  nn exp

 kT 
  eV0 
pn  p p exp

 kT 
Current flow in a forward-biased p-n junction
  eV0  V  
n p  nn exp

kT


  eV0  V  
pn  p p exp

kT


 eV 
n p  n p exp

 kT 
 eV 
pn  pn exp

 kT 
x

p( x )  pn ( x )  pn  p( x  0) exp
 Lh 
  eV  
p( x  0)  pn exp
  1
  kT  
  eV  
J  J 0 exp
  1
  kT  
 Dh
De 
J 0  e
pn 
n p 
Le 
 Lh
Current flow in a reverse-biased p-n junction
Junction geometry and depletion layer capacitance
E0 
 eN a x p
 0 r

 eN d xn
 0 r
1/ 2
 2 0
 1
1 

W  x p  xn  
(V0  V )

 N a N d 
 e
A  2e 0
Cj  
2 V0  V
1/ 2
 N d N a 


 N d  N a 
Zener breakdown under reverse bias
Semiconductor heterojunctions
Metal-semiconductor junctions
The quantum well and superlattice