What is effective mass of electron?
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).
What is effective mass of electron Formula?
The effective mass is determined by the band structure E(k). It can be calculated by mij-1= (2pi/h)2 d2E/d2kij.
How do you find the effective mass of an electron in a semiconductor?
the effective mass is determined by the band structure E(k). It can be calculated by mij-1 = (2pi/h)2d2E/dkij2.
Can effective mass of electron positive?
As one can see from the dispersion curves, the effective mass of the electrons in the valence band, m*V, is always negative. (This means that a force in +x direction will cause such an electron to move in –x direction.)
What is the effective mass of electron in Upper Valley?
The effective mass and mobility of the electrons in lower valley are 0.068 and 8000cm2/Vs whereas these quantities are 1.2 and 180 cm2/Vs in the upper valley of the n – type GaAs as shown below.
What do you mean by effective mass in semiconductor?
Introduction. The effective mass of a semiconductor is obtained by fitting the actual E-k diagram around the conduction band minimum or the valence band maximum by a parabola. Most semiconductors can be described as having one band minimum at k = 0 as well as several equivalent anisotropic band minima at k ¹ 0.
What is effective mass What is the relation between effective mass and mass of the spring?
The effective mass of a spring which is uniform along its length (not tapered or distorted by use) is equal to one-third of its actual mass. For a non-uniform spring, the effective mass can vary slightly with the attached mass; we will disregard this small variation.
When the effective mass of the electron is positive?
At k=0, electron has a constant positive value and it rises rapidly as k value increases. After experiencing a singularity (infinite mass) the effective mass becomes negative up to the top of the first BZ. Therefore: – m* is positive near the bottoms of all bands, – m* is negative near the tops of all bands.
Why effective mass of hole is greater than electron?
As the hole velocity is smaller, a hole spends more time in the interaction region, i.e. holes strongly interact with phonons. This leads to larger effective mass. In scientific words, phonon renormalization of the effective mass of holes is larger than that for electrons.
What do you mean by negative effective mass of electron?
The negative effective mass tells you that the electron responds to the field opposite to how a free electron would. Physically, the fact that the electron accelerates opposite to the direction of the force is because the electron must reflect off the zone boundary.