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What happens when electrons in conduction band loses its energy and falls to a hole in the valence band?
The energy leaves as either a photon or phonon.
Is the current in intrinsic semiconductos du to fre electrons or valence electrons and what is the diff between them?
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.
If a pure Si crystal has a million free electrons inside it how many holes does it have.what happens to the no of free electrons and holes if the ambient temperature increases?
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.
Why did Stephen perry the inventor invent the rubber band?
To hole all his paper work together
What causes a single pin hole in a spot weld?
may be a short squeeze time and high current without slope
What happens when electrons in conduction band loses its energy and falls to a hole in the valence band?
The energy leaves as either a photon or phonon.
What is recombination in electronics?
Process by which a conduction band electron gives up energy (in the form of heat or light) and falls into a valence band hole.
Why indirect band gap material is used for manufacturing LED's?
Optical sources like LEDs use direct band gap so that conduction band electorn can recombine directly with a hole in valence band .
Does hole exists practically in conduction of current?
A hole is a place where an electron is missing. Such places exist; and for practical purposes, it is convenient to think of them as independent positive charge carriers.
What is the effect of temperature on an intrinsic semiconductor?
An intrinsic semiconductor is basically a pure semiconductor, though some might argue that a small amount of doping can still yield an intrinsic semiconductor. In the crystal structure of this material, there are very few electrons crossing the band gap into the conduction band, and this stuff doesn't want to conduct much current. But as temperature increases, more electron-hole pairs will appear as electrons jump that band gap and take up places in the conduction band. And if you guessed that increasing temperature will permit the intrinsic semiconductor to conduct current flow a bit better, you'd be right. The intrinsic semiconductor has a positive temperature coefficient. More heat, more conduction under the same conditions.
What is heavy hole light hole and split-off hole?
the occupied highest band is the heavy band, the band prior below it is ligh band, the distance between two extremal points of those band is split-off band. At those points, hole is situated to be corresponding holes.
What happens when a silicon atom is replaced by a galium atom?
The regular electronic structure of 4 bonding electrons per atom is frustrated, because the gallium provides only 3. This situation is called "a hole in the valence band". If an electron jumps from a nearby silicon atom to fill this hole, there appears a hole where it came from (so it looks like the hole has moved, as it indeed has). This movement can be influenced by electric fields, and is called p-type, or hole, conduction (which is strictly electron movements in the "valence" band of the silicon).
Give some Examples of direct and indirect band gap semiconductors?
direct band gap-semiconductor in which the bottom of the conduction band and the top of the valence band occur at the momentum k=0;in the case of d.b.s. energy released during band-to-band electron recombination with a hole is converted primarily into radiation (radiant recombination); wavelength of emitted radiation is determined by the energy gap of semiconductor; examples of d.b.s. GaAs, InP, ZnS, ZnSs, CdS, CdSe etc. indirect bandgap semiconductor --semiconductor in which bottom of the conduction band does not occur at effective momentum k=0, i.e. is shifted with respect to the top of the valence band which occurs at k=0; energy released during electron recombination with a hole is converted primarily into phonon; e.g. Si, Ge, GaP, GaAsp ,Ge etc, .
What are the properties of semiconduter?
The properties are controlled by a "forbidden energy zone (known as the Band Gap" so that at low temperatures electrons from the constituent atoms do not have enough energy to populate available energy states above it (the "conduction band"). So there's no conduction there. They remain in an energy band closely associated with the parent atoms (the "valence band"), and since all the states are occupied, there's no conduction there either. By raising the temperature, electrons can be thermally excited from this lower state ("valence band") to the conduction band. So the conductivity is extremely dependent on temperature. By introducing small numbers of different atoms ("dopants") which have one more electron in their electronic structure ("donors") the extra electron which does not take part in the bonding is readily re-excited, with little added energy, into the conduction band. The semiconductor is then said to be "n-type". Equally, if a dopant is included which has one electron short to comply with the bonding arrangements, the is a "hole" in the valence band, and an electron hopping into this hole from a neighbouring atom, makes it seem like the hole has moved. Such a material is said to be "p type". All sorts of electronic devices, starting with diodes and transistors can be engineered by joining together pieces of p and n type material. For example a simple "junction" can be electrically biassed so that the electrons from the n type and the holes from the p type are pushed towards each other so they recombine (the electron drops into the space represented by the hole. This is called "forward bias of the diode". Reverse the bias polarity and the electrons and holes are pulled away from each other so eventually no current can flow ("reverse bias"), and the transient movement behaves like a capacitor. More complicated structures make transistors. And ever more complicated variations are possible.
When was Band Aid Covers the Bullet Hole created?
Band Aid Covers the Bullet Hole was created in 2002.
Why is the reverse saturation current of germanium diode more than silicon?
Germanium has four number of shells while Silicon has three number of shell. therefore for germanium less energy is required to move the electron from valence band to conduction band if compared to silicon. So at room temperature for germanium their are more number of electrons present in conduction bond hence more number of holes present in the valence energy band. Due to movement of holes reverse saturation current is produced. Their is more number of hole movement in germanium comparatively therefore reverse saturation current is more than silicon for germanium. You may refer to Electronic Devices and Circuits by Allen Mottershead Regards, Zain Ijaz UCTI, Malaysia Mechatronic Engineer.
Is the current in intrinsic semiconductos du to fre electrons or valence electrons and what is the diff between them?
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.
