SEMICONDUCTOR DEVICE PHYSICS AND DESIGN

158 CHAPTER 4. JUNCTIONS IN SEMICONDUCTORS:P-NDIODES

• ––


• ––


• –––


• ––


• –

}

}

Electron density in the

p-side depletion edge

EFp

EFn

++++

++++

++++

+++

+++

++

++

(a)

• ––
  
  
  • ––
  
  
  • ––
  
  
  • ––
  
  
  • –
  
  
  • 
    
  
  
  
  

++

+++

+++++

++++

++

+

+

EFp

EFn

(c)

V

• ––


• –


• ––


• ––


• –


• –

++

+++

++++

+++

+++

+++

EFp

V EFn

(b)

++

++

++

++

Fraction of electrons able to

be injected into the p-side Electron density versus

energy on the n-side

depletion edge

Zero bias:Diffusion current

= drift current

Fraction of holes able to

be injected into the n-side

Fraction of electrons able to

be injected into the p-side

Forward bias:

Diffusion current

>> drift current

Fraction of holes able to

be injected into the n-side

Negligible density of holes

able to cross the barrier

Negligible density of electrons

able to cross the barrier

Reverse bias:Diffusion current ~ 0

Figure 4.6: A schematic of the minority and majority charge distribution in then-andp-sides.
The minority carrier injection (electrons fromn-side top-side or holes fromp-side ton-side) is
controlled by the applied bias as shown.