We set a hypothesis semiconductor A and B with the following material parameters and

fabricate quantum structures as described in Question 1-3

Semiconductor A

Semiconductor B

Band gap (eV)

1.0

2.5

Electron affinity (eV)

4.5

3.5

Electron effective mass

0.05 mo

0.10 mo

Hole effective mass

0.2

0.2

1. (40pt) Firstly, we design double-hetero quantum well structure using the hypothesis

semiconductor A and B.

(a) (10pt) Draw the schematics of energy band diagram for double-hetero quantum well

structure. Find the ionization potential for both semiconductors. Also, find the barrier

heights for electron and hole.

(b) (10pt) What is the maximum of width of semiconductor well layer to observe the electron

confinement effect at 300K and 77K ?

(c) (10pt) Now, we fabricate the quantum well structure with the well width of 6 nm. Find all

the energy eigenvalues for conduction and valence subband levels by graphical methods

(You are required to show the plots)

(d) (10pt) Find the density of the states (DOS, D(E)) (the unit: ev"'nm") for the conduction

band for the above quantum well. Also, Plot the D(E)) for the quantum well structure.

2. (30pt) Here, we fabricate the tunneling, i.e. potential barrier, structure using these

hypothesis semiconductor A and B.

(a) (10pt) Find the transmission coefficient when the barrier width is 0.2nm, Inm, 2nm and

4nm. The energy of incident electron (E) is +0.1 eV.

(b) (10pt) Plot T(E) for the barrier thickness of 2nm, 4nm and 8nm (0 < E<7 eV).

(c) (10pt) Discuss about the condition to exhibit the T =1.