Question

Silicon doped with electron rich impurity forms__________.
A. p-type semiconductor
B. n-type semiconductor
C. Intrinsic semiconductor
D. Insulator

Answer 1

Hint: We will first understand the concept of doping and then, go through the options one-by-one. Doping is the purposeful introduction of impurities into an inherent semiconductor for the goal of altering its electrical, optical, and structural characteristics in semiconductor manufacturing.

Complete step by step solution:
Semiconductors are materials that have characteristics in the middle of the conductors and insulators. Semiconductors are used to make integrated circuits (ICs) and electronic discrete components like diodes and transistors. Example, Silicon, Germanium, etc.
Conduction in Semiconductor are of two types:
1) Intrinsic Conduction
2) Extrinsic Conduction
Intrinsic Conduction: Pure Silicon & Germanium are poor conductors because of the small gap in energy between conduction band & valence band. When sufficient energy is provided \[{e^ - }\] in the valence band will overcome the gap to reach the conduction band & thus conduct electricity.
Extrinsic Conduction: Top increase the conduction Semiconductors are doped. Doping is the process of addition of suitable impurity. These impurities are of two types:
1) Electron Rich
2) Electron Deficit
Electron Rich Impurity: \[V\] A group of elements such as Phosphorus \[(P),\] Arsenic \[(As)\] (or) Antimony \[(Sb)\] are used as doped. These elements have five \[{e^ - }\] in the valence shell, \[4\]these \[{e^ - }\] are used for bonding while extra \[{e^ - }\] conducts the electricity. This type of conductor is called n-type.
Electron Deficit Impurity: \[III\] A group element such as Boron \[(B),\] Indium \[(In)\] are used as dopes. These elements have three valence \[{e^ - }\]. Hence, they have an \[{e^ - }\] deficit spot. Where they conduct electricity by allowing \[{e^ - }\] into those deficit spots. These types of conductors are called p-type.
Therefore, Si doped with \[{e^ - }\] rich impurity forms n-type semiconductor.

Note: In n-type, conduction takes place due to electron movement away from impurity. In p-type, conduction takes place due to \[{e^ - }\] movement towards the impurity.