# Electro effective mass

1. Nov 3, 2008

### sarah1

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

2. Nov 5, 2008

### Dr Transport

The effective mass of electrons depending on how many bands you use in the $$\vec{k} * \vec{p}$$ 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. Nov 11, 2008

### Enthalpy

http://www.ioffe.ru/SVA/NSM/Semicond/
masses depend on the material, hence an encyclopaedia.