Heterojunction

As heterojunction (also heterostructure, Eng. Heterojunction ) is called the boundary layer of two different semiconductor materials. Unlike a PN junction, the doping type, but the material here is not (only ) are different. Therefore, the semiconductor A., possess a different energy of the band gap.

Heterojunctions are found in III- V semiconductors or II-VI semiconductors.

Calculation

In a pn heterojunction is an irregularity sets in the energy bands of the materials. The extension of this irregularity, a bending of the band edges, can be calculated via the Poisson equation. Assuming the transition from negative to positive 1 doped material doped material 2 with the relative dielectric constant and doping concentrations respectively, arises with the diffusion voltage in an applied external electric field, the voltage band bending of the following size a:

,

Application

Find application heterojunctions et al in the laser diode: recombination in optical radiation emitted in the area with the smaller band gap, they can not be absorbed by the electrons in the region of the larger band gap. The likelihood that the radiation leaving the semiconductor material is therefore greater.