MOSFET

What is the purpose of the LDD (lightly doped drain) structure in a MOSFET?

  1. ATo lower the resistance of the gate electrode
  2. BTo lower the doping at the drain edge, relax the electric field, and suppress degradation by hot carriers
  3. CTo double the channel mobility
Show answer and explanation

Answer: B. To lower the doping at the drain edge, relax the electric field, and suppress degradation by hot carriers

The electric field is strong near the drain, and high-energy carriers (hot carriers) are injected into the gate insulator, degrading the device characteristics. In the LDD structure, a lightly doped region on the channel side of the drain relaxes the field and suppresses this degradation.

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