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Can electron excitation happen in a semiconductor nanoparticle without light or thermal energy?
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What process is the opposite of thermal generation of electron hole pairs?
Recombination
What property of metallic bonds affect the thermal and electrical conductivity of metals?
electron negativity
An atom can be excited if it?
thermal agitation, electron impact, and photon impact
What is the source of energy for excited electrons?
There are several opportunities to excite electrons within an atom or a molecule. The energies to excite a single electron in an atom start at roughly 10-19J, which is approximately the energy of red light. Though, electrons can also be excited by any energies above roughly 10-25J (radar waves), dependent on the material. This also includes thermal excitation. For example, any material that glows does emit light, which is caused by excited electrons that fall back into a non-excited state. However, the usual source of energy used to excite electrons is electromagnetic radiation between 200 and 700 nm, which is ultraviolet and visible light. This is the predominant energy range that excites electrons in atoms and molecules without splitting the electrons apart of those. Thus, the colour of materials is (amongst other things) a result of the electron excitation, caused by partial absorption of light. (Please also follow the provided links for more details.)
Does metalloids have properties of both metals and inner transition metals?
Metalloids are unlike the inner transtion metals and all other metals. They are giant molecules whose bonding could be described as covalent. However consider silicon - perhaps the most widey used metalloid- it has a structure like diamond with tetrahedral bonds- but it is a semiconductor- this is because in molecular orbital terms the antibonding orbitals are sufficiently close to the energy of the bonding orbitals (band gap -using the nomenclature of band theory) for thermal excitation into the antibonding orbitals to take place.This is an oversimplification.
What is the difference between the minority charge carriers and majority charge carriers in diodes?
Majority charge carriers in the N-type side of a semiconductor material are electrons, because N-type semiconductor is doped with a material with 5 valence electrons. Semiconductor materials have 4 valence electrons and hold tightly to 8, so there is a "loose" electron for every atom of dopant. Therefore most of the charge carriers available are electrons. IE, electrons are the majority charge carriers. Minority charge carriers in N-type semiconductor are holes. Only a few holes (lack of an electron) are created by thermal effects, hence holes are the minority carriers in N-type material. The situation is reversed in P-type semiconductor. A material having only 3 valence electrons is doped into the semiconductor. The semiconductor atoms have 4 valence electrons try to hold tightly to 8, so there is a virtual hole created by a "missing" electron in the valence orbit. This acts as if it were a positive charge carrier. Most of the charge carriers are these holes, therefore in P-type semiconductor holes are the majority charge carrier. Again, reverse situation to minority charge carriers. Some electrons are loosened by thermal effects, they are the minority charge carriers in P-type semiconductor.
What is solar thermal energy and how it works?
When solar light is absorbed by a material (usually dark colored when dealing with capturing solar energy) it is converted to thermal energy (heat). This can then be transferred by air, water, or conduction. I suppose if you think of heat as the excitation level of molecules in a substance. Then the absorption of photons would increase the excitation of those molecules.
What is an intrinsic semiconductor and what is an extrinsic semiconductor?
intrinsic semiconductor is an un-doped semiconductor, in which there is no impurities added where as extrinsic semiconductor is a doped semiconductor, which has impurities in it. Doping is a process, involving adding dopant atoms to the intrinsic semiconductor, there by gives different electrical characteristics
Is a diamond an insulator?
Diamond is usually a good insulator, and as it also has the highest thermal conductivity, these properties are used as a substrate under semiconductor chips for extracting the heat. But some blue diamonds are a semiconductor, due to boron trace contamination, and these are used as a semiconductor material.
What process is the opposite of thermal generation of electron hole pairs?
Recombination
Do free electrons and holes in a semiconductor individually contribute to current flow so that the net current is the sum of these two currents?
For a Semiconductor sample which is not disturbed from equilibrium. This is true:A: The understanding is that negative electrons flow leaving a hole This is the result of an electron leaving its orbit, both are motions of direction except in opposite directions so the net sum of both is zero not accumulated.However, when the semiconductor sample is perturbed by, for example, applied potential difference and/or thermal gradient and/or optical generation etc.The individual carriers will contribute to the total current.
What happens to the energy of semiconductor when the temperature of the room increases?
When electrons are given energy, they can "jump" to a higher energy level or "electron shell". It would then be in an excited state. When it returns, it will emit the energy in the form of an electromagnetic wave (light). A good example is a simple filament lightbulb. Electrons undergo thermal excitation (excited by heat) and will emit a whole range of electromagnetic waves (in the visable region of the spectrum, but also a lot of lower energy infra red light)
What are thermally generated electrons and holes?
In any semiconductor (doped or not) vibrations of the atoms in the crystal can sometimes knock electrons out of the atom's valence band into the conduction band. When this happens the electron now in the conduction band is added to the population of electrons in the semiconductor, while the void it left behind in the valence band is added to the population of holes in the semiconductor. As the vibrations that cause this generation of electron and hole pairs are usually thermal (although there are other causes too) they are usually called thermally generated electrons and holes.Since the electron and hole pair are in close proximity when formed, many of them recombine before they could be separated by an electric field in the crystal or by simple diffusion.There is of course a somewhat more complicated (but also more correct) explanation using Quantum Mechanics, but the above is sufficient to understand it at the first approximationlevel.
Is carbon good conductor of heat?
add. Diamond is an excellent conductor of heat - second only to graphene, and superior to silver. It is used as a thermal substrate for some semiconductor chips.have a crack at 'thermal conductivity' in wikipedia.
Is sulphur a thermal insulator?
Sulphur is one of the best thermal insulators known, possibly due to the fact that electron-attracting terminal atoms are present.
What property of metallic bonds affect the thermal and electrical conductivity of metals?
electron negativity
An atom can be excited if it?
thermal agitation, electron impact, and photon impact
