What is EC in semiconductor?
Ev and Ec represent the top of the valence band and the bottom of the conduction band. So that the energy distance between them is the band gap (Eg). The top of the conduc- tion band is the vacuum level and is usually Ec + χ above the conduction band where χ is the electron affinity of Si.
How is semiconductor carrier concentration measured?
Calculation. The carrier density is usually obtained theoretically by integrating the density of states over the energy range of charge carriers in the material (e.g. integrating over the conduction band for electrons, integrating over the valence band for holes).
What are the electron and hole concentrations at 300k?
Question: Electron and Hole Concentrations The electron concentration in a piece of Si at 300 K is 10^5 cm^-3. A semiconductor is doped with impurity concentrations N_d and N_a such that N_d – N_a >> n_i and all the impurities are ionized.
What is electron and hole in semiconductor?
Holes and electrons are the two types of charge carriers responsible for current in semiconductor materials. A hole is the absence of an electron in a particular place in an atom. In N-type semiconductor material, electrons are the majority carriers and holes are the minority carriers.
What is hole concentration?
In a similar way, at room temperature or elevated temperatures, each acceptor creates one hole in the valence band, and the hole concentration, p, in the valence band of a p-type semiconductor is approximately equal to the acceptor concentration, Na.
What is NC and NV in semiconductors?
Nc and Nv, the effective density of states at the band edges, are dependent on temperature and the effective mass of the electron and holes respectively. For Si, m∗
What is N-type semiconductor?
An n-type semiconductor is an intrinsic semiconductor doped with phosphorus (P), arsenic (As), or antimony (Sb) as an impurity. Silicon of Group IV has four valence electrons and phosphorus of Group V has five valence electrons. When this free electron is attracted to the “+” electrode and moves, current flows.
What is a hole semiconductor?
A hole can be seen as the “opposite” of an electron. Unlike an electron which has a negative charge, holes have a positive charge that is equal in magnitude but opposite in polarity to the charge an electron has. These semiconductors, where holes are the most prominent charge carrier, are known as p-type.
What do you mean by hole of semiconductor?
Answer: Holes are formed when electrons in atoms move out of the valence band (the outermost shell of the atom that is completely filled with electrons) into the conduction band (the area in an atom where electrons can escape easily), which happens everywhere in a semiconductor.
What are the electron and hole concentrations?
For an intrinsic semiconductor, the concentration of electrons in the conduction band is equal to the concentration of holes in the valence band. The doping process can greatly alter the electrical characteristics of the semiconductor. This doped semiconductor is called an extrinsic material.
What are holes in semiconductors?
Holes are formed when electrons in atoms move out of the valence band (the outermost shell of the atom that is completely filled with electrons) into the conduction band (the area in an atom where electrons can escape easily), which happens everywhere in a semiconductor.
What is the hole concentration of a semiconductor?
Proceeding as we did for electrons, the hole concentration in a non- degenerate semiconductor is: p = Nv e (EF-Ev)/ (kT) (3.15) Nv – i m^) (3.16) In this case Nv is called the effective density of states in the valence band.
How to calculate the electron and hole concentrations?
A very useful equation, called the law of mass action for charge carrier concentrations, can be derived from the above expressions for the electron and hole concentrations. In effect, from Eqs (3.12) and (3.15), we have: np = NcNv e- (Ec-Ev)/ (kT) = NcNve-Eg/kT = const (T)
Why is the constant NT important in semiconductors?
The constant nt has a special significance because it represents the free electron and hole concentrations in the intrinsic material. An intrinsic semiconductor is a pure semiconductor crystal in which the electron and hole concentrations are equal.
How are electron and hole concentrations related to Fermi level?
The electron and hole concentrations are closely linked to the Fermi level. The materials introduced in this chapter will be used repeatedly as each new device topic is introduced in the subsequent chapters.