Question

Silicon can be doped using one of the following elements as dopant:
(A) Arsenic
(B) Indium
(C) Phosphorus
(D) Boron.
To get an n-type semiconductor, the dopants that can be used are______.
Fill in the blank with the correct answer from the options given below.

• A. (A) and (C) only
• B. (B) and (C) only
• C. (A), (B), (C), and (D)
• D. (C) and (D) only

Answer 1

The Correct Option is A

To determine which elements can be used to dope silicon to create an n-type semiconductor, we need to understand a few key concepts:

• An n-type semiconductor is formed when the dopant atoms introduce additional electrons into the material, providing excess negative charge carriers.
• Dopants for n-type semiconductors are typically elements with five valence electrons (Group 15 elements in the periodic table).
• Silicon has four valence electrons; thus, adding an element with five valence electrons provides an extra electron that can be a free carrier for conduction.

Now, let's analyze the dopants:

• Arsenic (A): A Group 15 element with five valence electrons.
• Indium (B): A Group 13 element with three valence electrons; typically used for p-type doping.
• Phosphorus (C): A Group 15 element with five valence electrons.
• Boron (D): A Group 13 element with three valence electrons; used for p-type doping.

Considering these characteristics, only Arsenic (A) and Phosphorus (C) have the appropriate number of valence electrons to act as donor atoms and create an n-type semiconductor in silicon. Thus, the correct answer is: (A) and (C) only.

Answer 2

To determine the dopants that can create an n-type semiconductor in silicon, we need to understand the concept of doping.

Doping:

Doping involves adding impurities to a semiconductor to alter its conductivity.

n-type Semiconductor:

An n-type semiconductor is created by adding impurities with more valence electrons than silicon (which has 4 valence electrons). These impurities donate extra electrons, increasing the number of free electrons and thus the conductivity.

p-type Semiconductor:

A p-type semiconductor is created by adding impurities with fewer valence electrons than silicon. These impurities create "holes" (electron vacancies), which act as positive charge carriers, increasing conductivity.

Analysis of Dopants:

• (A) Arsenic (As): Arsenic has 5 valence electrons. It can donate an extra electron, making silicon an n-type semiconductor.
• (B) Indium (In): Indium has 3 valence electrons. It creates holes, making silicon a p-type semiconductor.
• (C) Phosphorus (P): Phosphorus has 5 valence electrons. It can donate an extra electron, making silicon an n-type semiconductor.
• (D) Boron (B): Boron has 3 valence electrons. It creates holes, making silicon a p-type semiconductor.

Therefore, to create an n-type semiconductor, we can use Arsenic (A) and Phosphorus (C).

The correct answer is:

Option 1: (A) and (C) only