There are no free electrons and holes in a pure semiconductor at 0k.
increases
Well intrinsic semiconductor is semiconductor crystal with no impurities in it. In intrinsic semiconductor the electrons in valence band(valence electrons) gain energy(due to thermal enegry) and break free into conduction band(means it become free electrons). As this electron breaks free, a vacancy is created in place of it. It is called as a hole. This hole has a positive charge. So current in semiconductor is due to flow of this free electrons and holes. But this current is very small in magnitude. The difference between free electrons and valenece electrons is that valence electrons are often bonded to other atoms in crystal. But free electrons can freely move throughout the crystal.
Semiconductor in pure form (i.e. without doping) is called intrinsic or i-type semiconductor. The no of charge carrier in this case is determined by the materials itself only and not by the impurities. In an intrinsic semiconductor number of excited free electron is equal to the number of holes.
If the crystal is pure Si (no dopants or impurities) then the number of free electrons in the conduction band will be equal to the number of holes in the valence band. Each electron leaves behind a hole when it is thermally excited into the conduction band. If the ambient temp. increases, there will be more thermal energy available which will increase both the number electrons and the number of holes.
silicon has 4 valence electrons leaving a half empty shell sharing electrons covalently with its neighbors leaving no free electrons, copper has 1 valence electron which is so loosely bound it forms an electron gas which conducts easily. silicon can be doped with tiny amounts of impurities having 5 or 3 valence electrons, providing free electron or missing electrons called holes to carry current.
increases
p-type semiconductor is obtained by carrying out a process of doping that is by adding a certain type of atoms to the semiconductor in order to increase the number of the free charge carriers.
Well intrinsic semiconductor is semiconductor crystal with no impurities in it. In intrinsic semiconductor the electrons in valence band(valence electrons) gain energy(due to thermal enegry) and break free into conduction band(means it become free electrons). As this electron breaks free, a vacancy is created in place of it. It is called as a hole. This hole has a positive charge. So current in semiconductor is due to flow of this free electrons and holes. But this current is very small in magnitude. The difference between free electrons and valenece electrons is that valence electrons are often bonded to other atoms in crystal. But free electrons can freely move throughout the crystal.
Doping with Group III elements, which are missing the fourth valence electron, creates "broken bonds" (holes) in the silicon lattice that are free to move. The result is an electrically conductive p-type semiconductor.
Semiconductor in pure form (i.e. without doping) is called intrinsic or i-type semiconductor. The no of charge carrier in this case is determined by the materials itself only and not by the impurities. In an intrinsic semiconductor number of excited free electron is equal to the number of holes.
If the crystal is pure Si (no dopants or impurities) then the number of free electrons in the conduction band will be equal to the number of holes in the valence band. Each electron leaves behind a hole when it is thermally excited into the conduction band. If the ambient temp. increases, there will be more thermal energy available which will increase both the number electrons and the number of holes.
semiconductor
Generally electrons, in metal. Specifically loosely-bound electrons from the outer orbital. Or holes, in p-type semiconductor. Or ions, in conducting liquid like battery acid. Or electrons, in a cathode-ray-tube.but i conclude it would be electrons. OR Q-which charges are more free to move in a conductor. A-electrons
because its valence electrons are free and it is used to the free moving of electrons..so they are used as semiconductors
The main reason semiconductor materials are so useful is that the behavior of a semiconductor can be easily manipulated by the addition of impurities, known as doping. Semiconductor conductivity can be controlled by introduction of an electric or magnetic field, by exposure to light or heat, or by mechanical deformation of a doped mono-crystalline grid; thus, semiconductors can make excellent sensors. Current conduction in a semiconductor occurs via mobile or "free"electrons and holes. collectively known as charge carriers. Doping a semiconductor such as silicon with a small amount of impurity atoms, such as phosphorus or boron. greatly increases the number of free electrons or holes within the semiconductor. It can be make in very small size and the electronics device are small in size that why the semiconductors are used in electronic devices. The above explains HOW semi conductors work. The reason for WHY they are used is, what's the alternative? The only alternative is thermionic valves (tubes). Tubes fell out of favour for many reasons. They run hot Made of glass and delicate, Heavy Large Consume lots of power Need high voltages. Semi conductors are the opposite of all of these.
1.By doping 2.by shining light on the surface of semiconductor materials 3.by increasing temperature
Donor atoms are those impurity atoms in a semiconductor material that give free electons to the material, for example a 5-valent atom in a semiconductor consisting of 4-valent atoms. Acceptor atoms are 3-valent atoms in a 4-valent semiconductor, so an acceptor atom can "accept" an electron from the surrounding atoms what leaves a free "hole" . Free electrons (from donor atoms) and free holes (from acceptor atoms) make the semiconductor conduct electricity.