Density-Of-States (DOS) and Conductivity Effective Masses
In Appendix IV, we calculated the effective mass matrix for one minimum energy point (or valley). As mentioned in the same appendix, however, there can be multiple valleys or degenerate bands in the band structure. In such cases, the effect of all valleys or degenerate bands should be considered. When we calculate the effect of multiple valleys or degenerate bands, we have to exercise caution in combining the values of the effective mass matrix elements. There are two distinct categories of effective masses: one is the density-of-states (DOS) effective mass, and the other is the conductivity effective mass.
The DOS effective mass is introduced to express the density of states ...