What is effective mass in semiconductor?
What is effective mass in semiconductor?
The effective mass is a quantity that is used to simplify band structures by modeling the behavior of a free particle with that mass. For electrons or electron holes in a solid, the effective mass is usually stated in units of the rest mass of an electron, me (9.11×10−31 kg).
How do you find the effective mass of a semiconductor?
the effective mass is determined by the band structure E(k). It can be calculated by mij-1 = (2pi/h)2d2E/dkij2.
What is a split off band?
Many common semiconductors such as Si, Ge, and GaAs have a split-off band just below the valence band. The states in the split-off band change the temperature dependence of the concentration of holes.
What is effective mass formula?
The effective mass is determined by the band structure E(k). It can be calculated by mij-1= (2pi/h)2 d2E/d2kij. Furthermore, it can be measured by cyclotron resonanz.
How do you derive effective mass?
This mass of an electron is called the effective mass of an electron, denoted as m*. The effective mass is thus determined by d 2E/dK 2. From band theory of solids, we know E is not proportional to K 2. , which is the top of the band.
How do you measure effective mass?
1. As you have mentioned normally, “Effective masses” were measured using cyclotron resonance, a method in which microwave absorption of a semiconductor immersed in a magnetic field goes through a sharp peak when the microwave frequency equals the cyclotron frequency.
What is heavy hole band?
The heavy holes tend to dominate the properties of the valence-band extremum; their heavier effective mass means that their density of states will be much larger than that of the light holes (see Section 5.2. 4).
What are heavy holes?
light hole band is steeper & heavy hole band flatter and they are located in the valence band and are degenerate bands. As the names say heavy holes are in the heavy hole band and light holes in the light hole band, meaning the effective mass m* of heavy holes mhh is larger than of light holes mlh.
Does Hole have mass?
Based on the relation E = mc^2 , Energy of hole is greater than that of electron, thus holes have mass greater than that of electrons. The only difference between electrons and holes is in their energy and, therefore, in velocity. The effective mass is a result of electron interaction with lattice, i.e. with phonons.