SEMICONDUCTOR DEVICE PHYSICS AND DESIGN

504 CHAPTER 10. COHERENT TRANSPORT AND MESOSCOPIC DEVICES

Junction with "Coulomb Blockade"

• –


• –

I

V

I

V

• –

I

V

I

V

I

V

• 
  
  
  
  • 
    
  
  
  
  


• –
  Charging
  energy

Junction without "Coulomb Blockade"

Tunneling

allowed

Tunneling not

allowed

Non-linear I-V

Monotonic I-V

Figure 10.12: (a) A tunnel junction with large capacitance shows ohmic I–V characteristics.
(b) In very small capacitance tunnel junctions the presence of a Coulomb blockade ensures no
current flows until the voltage reaches a threshold value determined by the charging energy.