513.001 Molecular and Solid State Physics

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Wolfram Alpha

Physical
Constants

Periodic System
of Elements

      

Chemical potential of Ge

The effective densities of states for several semiconductors are given below.

Nc

Nv

Eg

 Si (300 K)

2.78 × 1025 m-3

9.84 × 1024 m-3

1.12 eV

 Ge (300 K)

1.04 × 1025 m-3

6.0 × 1024 m-3

0.66 eV

 GaAs (300 K) 

 4.45 × 1023 m-3 

7.72 × 1024 m-3

1.424 eV

What is the chemical potential energy for intrinsic Ge measured from the top of the valence band at 300 K?

Draw the density of states for Ge as a function of energy near the top of the valence band and the bottom of the conduction band.

Germanium is an indirect semiconductor. The valence band maximum is at k = 0 but the conduction band minimum is in the <111> direction. How many conduction band minima are there?

Describe the relationship between the effective density of states and the effective mass. (You don't need to give the formula, just describe in words how they are related.)