Question

Arrange the following according to increasing order of their dimensionality:
A. Quantum well,
B. Quantum wire,
C. Bulk material,
D. Quantum dot.

• A. A \(<\) B \(<\) C \(<\) D
• B. C \(<\) A \(<\) D \(<\) B
• C. B \(<\) C \(<\) D \(<\) A
• D. D \(<\) B \(<\) A \(<\) C

Hint:

Quantum dot is \(0D\), quantum wire is \(1D\), quantum well is \(2D\), and bulk material is \(3D\).

Answer 1

The Correct Option is D

Concept:
Nanostructures are classified according to how many dimensions are free for carrier motion.

Step 1: Quantum dot.
A quantum dot confines carriers in all three directions. So, it is: \[ 0D \] Thus, \[ D=0D \]

Step 2: Quantum wire.
A quantum wire allows motion only in one direction. So, it is: \[ 1D \] Thus, \[ B=1D \]

Step 3: Quantum well.
A quantum well allows motion in two directions and confines motion in one direction. So, it is: \[ 2D \] Thus, \[ A=2D \]

Step 4: Bulk material.
Bulk material allows motion in all three directions. So, it is: \[ 3D \] Thus, \[ C=3D \]

Step 5: Arrange in increasing order. \[ 0D<1D<2D<3D \] \[ D<B<A<C \] \[ \therefore \text{Correct Answer is (D)} \]