Shockley Diode

Shockley Diode

1. Structure

   • PNPN device
     • Four alternate P-Type and N-type layers in a single crystal
       • Layers
         • P1, N1 , P2 , N2
           • P- region adjacent to an N-region may be consuidered a junction diode
             • Is equivalent to three juction diodes connected in series
   • Have two terminals
   • Acts as a switch
   • Present a very high resistance

2. 1

   • Foward-biased
     • D1 and D3
   • Reverse- biased
     • D2
       • Offers very high resistance
   • Foward voltage increases
     • Reverse bias across D2 Increased
   • At some Foward Voltage (breakover voltage Vbo)
     • Reverse breakdown of D2 occurs
   • Since this breakdown results in reduced resistance, the Shockley diode presents a very low resistance.

3. 2

   • When the diode is reverse biased
     • Anode is negative w.r.t cathode
   • Reverse- Biased
     • D1 and D3
   • Foward-Biased
     • D2
   • IF Reverse voltage increased
     • Reverse voltage breakdown
       • Shockley diode is reached.

4. Conclusion

   • So long as the forward voltage is less than breakover voltage
     • Very high resistance (ie., switch is open) and practically conducts no current.
   • At voltages above the break-over value,
     • Shockley diode presents a very low resistance (i.e. switch is closed) and Shockley diode conducts heavily.

Imágenes y archivos del mapa