Additional Effective Mass Concepts

The curvature of the E versus k diagrams near the minimum of the conduction ban energy is related to the effective mass of the electron. We may note from Figure 1.1 that the curvature of the conduction band at its minimum value for GaAs is large than that of silicon, so the effective mass of an electron in the conduction hand of GaAs will be smaller than that in silicon.

For the one-dimensional E versus k diagram, the effective mass was defined as l/m^* = 1/h² . d² E/d k². A complication occurs in the effective mass concept in a real crystal. A three-dimensional crystal can be described by three k vectors. The curvature of the E versus k diagram at the conduction band minimum may not be the same in the three k directions. We will not consider the details of the various device calculations. effective mass parameters here. In later sections and chapters, the effective mass parameters used in calculations will be a land of statistical average that is adequate for most