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- Silicon is opaque to all light (IR through UV).
- The bandgap of silicon is not high enough to produce visible photons, only IR photons.
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∙ 11y ago
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Why silicon does not emit light?
I agree with Binitha on the point that Silicon is an indirect band gap semiconductor.
What is a ordinary diode?
A diode is an electronic component that will only allow current to flow through it in one direction. It is analogous to the valve in a bicycle tyre, which only lets air in but not out (except when you press the release tab). So if you connect a diode in a simple DC circuit one way around, the circuit will be closed and any devices on the circuit will work. If you connect it the other way around the circuit is open and no current will flow. I presume by 'ordinary diode' you mean a diode that is not a light emitting diode (LED). A LED is just a diode that emits light when current flows through it. Its purpose is to make light. A non-LED diode doesn't emit light. Its purpose is to allow current through a circuit in only one direction. A common use for ordinary diodes is in "rectifying circuits" which convert AC to DC.There are many other uses though.
Do you see a light when the LED diode in the reverse bias?
Not usually, unless you mean a LED. It depends of the kind of diodes. LEDs will emit light but not most regular diodes, though some may produce infrared light. In the case of LEDs, the answer is yes. When an electron crosses the PN junction and falls into a hole, it emits a photon. The frequency depends on the energy, which is determined by the forward bias voltage. That is why a red LED requires more voltage than an IR LED, and less than a green LED. So a regular diode with a forward drop of about 0.7V is emitting infrared (IR) light. However, most of the photons are reabsorbed in the semiconductor body or stopped by an opaque case. An LED is a special diode doped for a higher voltage and constructed to let as many of the photons out as possible, set in a reflector and usually with a lens cast into the plastic case. There are a few glass-cased diodes which emit a deep red light, that I observed in a few audio amps. They drop more than the typical silicon diode's 0.7V. But overall, you typically cannot see the light emitted in a rectifier diode due to the absorption of the case and the semiconductor itself, and the fact that it is usually infrared. You might try some experiments yourself by removing the IR blocking filter that is normally installed in webcams, or find an IR sensitive security camera. All CCDs (the light sensing element in a video camera, digital camera, or webcam) are sensitive to infrared, but most have had a filter added to block IR so as not to spoil your photos. Then get some glass cased silicon diodes, point contact will have more viewing space, and a 9V battery and a 220 ohm resistor to put in series to limit the current. This will give you about 36mA through the diode. Then point the camera at it and turn out the lights or put it in a light-tight box and look for a glow from the diode.
What is LED?
An LED is a Light Emitting Diode. It is a semiconductor device designed to produce a certain type, wavelength, etc. of light. As opposed to an LCD which is a Liquid Crystal Display, does not emit light of any real intensity, although excitation methods have been developed for use in TV's, cellphones, etc. More common now than LED's. The major difference is that LED's have to have power all the time to emit. LCD's just need power to change. So, they are more energy efficient.
What is the difference between silicon and germanium semiconductors?
integrated circuits and components made in GaAs are much faster than silicon because its low field electron mobility is larger than silicon. GaAs has ability to emit light used in leds,lasers and microwave emitter used in cellular phones
What materials will emit light when electricity is added?
Light emitting diodes will emit light when electicity is passed through them.
Why Silicon and germanium emit light?
they emit heat when their is a recombination of electron and holes
Why silicon does not emit light?
I agree with Binitha on the point that Silicon is an indirect band gap semiconductor.
Is light emitting diodes emit visible light when forward biased?
It depends on the particular LED. Some of them emit infrared light. But, yes, emission occurs when forward-biased.
What makes lasers laze?
the lasers are pumped or energized by rays of laser diodes. then the laser diodes emit laser light into the semi conductor rod to cause it to laze. the semiconductor rod is stimulated to emit a high coherent light impulse
Why ordinary silicon diode does not emit light?
The energy band gap between the cathode and anode is too small to generate photons of higher energy than far IR.Silicon is opaque to visible light (and even IR).
What is a ordinary diode?
A diode is an electronic component that will only allow current to flow through it in one direction. It is analogous to the valve in a bicycle tyre, which only lets air in but not out (except when you press the release tab). So if you connect a diode in a simple DC circuit one way around, the circuit will be closed and any devices on the circuit will work. If you connect it the other way around the circuit is open and no current will flow. I presume by 'ordinary diode' you mean a diode that is not a light emitting diode (LED). A LED is just a diode that emits light when current flows through it. Its purpose is to make light. A non-LED diode doesn't emit light. Its purpose is to allow current through a circuit in only one direction. A common use for ordinary diodes is in "rectifying circuits" which convert AC to DC.There are many other uses though.
What makes a normal diode a LED?
There are diodes and there are diodes LED are made from arsenic doping to emit photons are never used for other purposes other then LED
Do light bulbs emit light or suck dark?
Light bulbs emit light.
Are energy saving bulbs ultra violet light?
They may emit some energy in that wavelength, but most of their output is in the ordinary visible band.
Does technetium emit light?
Technetium doesn't emit light.
Do galaxies emit light?
Yes galaxies emit light
