Question

Difference between multiple quantum well and superlattice

Answer 1

It can also refer to a lower-dimensional structure such as an array of quantum dot or quantum wires. 3. INTRODUCTION  A semiconductor superlattice is a periodic structure of two or more semiconductors of significantly different band gaps such that multiple quantum wells are formed in the low band gap layers.

Answer 2

Answer:

The diffrence between the  multiple quantum well and superlattice are as under-

Explanation:

Multiple quantum well

Quantum wells are nanometer wide layers of a lower band gap semiconductor grown on a higher band gap barrier material.The defining feature of MQWs is that the barriers are wide enough such that wavefunctions in adjacent quantum wells do not overlap.

Superlattices

The defining feature of a superlattices is  the wavefunctions of adjacent wells overlap strongly, that the barriers are very thin such that. This means that electrons in superlattices are delocalised because they can easily tunnel out.

A system is called  multiple quantum well or superlattice on the basis of-

width of the band If the bandwidth is small enough (in comparison with temperature, characteristic times, etc., whatever is important for  problem) and we may consider carriers as localized within definite QW and jumping between them, we call this MQW. Width of band is formed by interaction of the levels in adjoint MQWs.

If the bandwidth is large  and this is more electron distributed between many QWs then we call this superlattice.

E.g., the same structure can be-

• MQW at low temperatures and
• superlattice at room temperature.