The model solid approximation is a method used for determining the extrema of energy bands in semiconductors. The method was first proposed for silicon-germanium alloys by Chris G. Van de Walle and Richard M. Martin in 1986[1] and extended to several other semiconductor materials by Van de Walle in 1989.[2] It has been used extensively for modelling semiconductor heterostructure devices such as quantum cascade lasers.[3]
Although the electrostatic potential in a semiconductor crystal fluctuates on an atomic scale, the model solid approximation averages these fluctuations out to obtain a constant energy level for each material.
References
^Van de Walle, Chris G.; Martin, Richard M. (1986-10-15), "Theoretical calculations of heterojunction discontinuities in the Si/Ge system", Phys. Rev. B, 34 (8): 5621, Bibcode:1986PhRvB..34.5621V, doi:10.1103/PhysRevB.34.5621