# Solid State Electronic Device

Discussion in 'Electronics Homework Help' started by vick5821, Jun 5, 2012.

1. ### vick5821

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Jan 22, 2012
If energy gap, Eg of GaAs is 1.43eV, calculate the wavelength of the compound and comment on the spectrum that will be observed.

I have calculated the wavelength. But How do I know whether it can be observed in which spectrum ?

Thank you

3,635
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Apr 7, 2012
3. ### vick5821

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Jan 22, 2012
So 0.87micro meter should be which?

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,497
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Jan 21, 2010
It would be very close to 870 nm. And you can google for what colour that is.

5. ### vick5821

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Jan 22, 2012
colour ? LOL..thought spectrum ?

6. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,497
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Jan 21, 2010
Isn't light part of the electromagnetic spectrum?

7. ### vick5821

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Jan 22, 2012
Yea..but is 870nm in infrared spectrum ?

8. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
Well there you are. That's what spectrum it's in!

9. ### vick5821

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Jan 22, 2012
That is the answer given by my lecturer.But I dun get how to determine it from the spectrum ? 870nm is higher than 100nm.So it suppose to be very near to visible light region is it ?

10. ### CocaCola

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Apr 7, 2012
Did you look at a chart, the one I posted? Human visible light is in the 390-750nm range give or take...

870nm is infrared just outside human visible range
100nm is ultraviolet, well outside human visible range

11. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,497
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Jan 21, 2010
IR is right next door to visible light.

Indeed, you'll often find it listed in the visible spectrum even though it's not visible.

The names given to parts of the electronic spectrum are man-made and really exist as a rough shorthand. Often (well, almost always) there is little to distinguish wavelengths that are just inside or just outside the defined region.

Most of the shorter spectra is grouped by wavelength. For lower frequency spectra wavelength tends to give way to frequency.

Knowing what each part of the spectrum is named is purely a memory exercise (except maybe the visible spectrum!)

12. ### vick5821

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Jan 22, 2012
So what I meant is 870nm is very closed to the visible light region. Correct ? Haahaha.

Thanks man

13. ### davennModerator

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Sep 5, 2009
close but still well out of the visible range

Dave