Effective Mass in Indirect Band Gap Semiconductors

In summary, the effective mass in indirect band gap semiconductors is not constant due to the anisotropy of the effective mass. This results in both longitudinal and transverse effective masses. To calculate the optical parameters in semiconductors, both electron and hole effective masses are needed, and in indirect band gap materials, the electron effective mass will also be anisotropic. Additionally, a phonon assist is needed for calculations in indirect materials. The masses are material-dependent and can be found in an encyclopedia such as the one provided by the Ioffe Institute.
  • #1
sarah1
6
0
in indirect band gap semiconductors ,the effective mass isn't constant , because of the anisotropie of this effective mass there are (longitidinal and transversal effective mass). for calculate the optical parameters in semiconductor , i need electron and hole effective masses , what the value of electron effective mass in this type of semiconductors ( transversal or longitidinal ?)
thank you
 
Physics news on Phys.org
  • #2
The effective mass of electrons depending on how many bands you use in the [tex]\vec{k} * \vec{p} [/tex] calculation will be isotropic in a direct material. The hole effective masses will not be, and you need to know both transverse and longitudinal masses to calculate optical properties. In an indirect band gap material, the electron effective masses will be anisotropic and again, you need to know both the transverse and longitudinal masses for your calculation. it must also be remembered that in indirect materials there is the need for a phonon assist to complete the calculation.
 
  • #3
http://www.ioffe.ru/SVA/NSM/Semicond/
masses depend on the material, hence an encyclopaedia.

Bookmark the address, you need it if it's your job.
 
  • #4
I love The Russian page.
 

1. What is effective mass in indirect band gap semiconductors?

Effective mass in indirect band gap semiconductors refers to the mass of an electron or hole that behaves as if it were free in a specific energy band. It is a measure of the particle's mobility and determines how easily it can move within the crystal lattice of a semiconductor.

2. How is effective mass different from actual mass?

Effective mass is different from actual mass because it takes into account the influence of the crystal lattice on the motion of electrons and holes in a semiconductor. In contrast, actual mass refers to the physical mass of the particle. Effective mass can be thought of as an "effective" or averaged value of the actual mass in a specific energy band.

3. Why is effective mass important in indirect band gap semiconductors?

Effective mass is important in indirect band gap semiconductors because it affects the electronic and optical properties of the material. It plays a crucial role in determining the conductivity, carrier mobility, and absorption coefficient of a semiconductor, which are important factors in the design and performance of electronic devices.

4. How is effective mass measured in indirect band gap semiconductors?

Effective mass in indirect band gap semiconductors is typically measured using spectroscopic techniques, such as photoluminescence or photoconductivity measurements. These techniques involve exciting the material with light of different wavelengths and analyzing the resulting changes in the material's electronic properties to determine the effective mass.

5. Can effective mass be modified in indirect band gap semiconductors?

Yes, effective mass can be modified in indirect band gap semiconductors by changing the material's composition, crystal structure, or doping levels. This can be done through techniques such as alloying, strain engineering, or impurity doping, which can alter the electronic properties of the material and thus affect the effective mass.

Similar threads

  • Atomic and Condensed Matter
Replies
2
Views
967
  • Atomic and Condensed Matter
Replies
1
Views
995
  • Atomic and Condensed Matter
Replies
2
Views
1K
  • Atomic and Condensed Matter
Replies
2
Views
1K
  • Atomic and Condensed Matter
Replies
3
Views
1K
  • Atomic and Condensed Matter
Replies
7
Views
403
  • Atomic and Condensed Matter
Replies
2
Views
3K
  • Atomic and Condensed Matter
Replies
2
Views
2K
  • Atomic and Condensed Matter
Replies
1
Views
1K
  • Atomic and Condensed Matter
Replies
2
Views
3K
Back
Top