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Author Topic: Has anyone experimented with diamond as a semiconductor?  (Read 4584 times)

Offline AndroidNeox

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Now that we can create diamond films via vapor deposition, it seems like we could experiment with it as an electronic substrate. Since it's a semiconductor, it seems like it might be possible to dope it (presumably with Boron and Nitrogen) to create p- and n-type materials, respectively.

Diamond has some physical properties that seem like it could be ideal. It has the highest electrical breakdown voltage and makes the best insulator. It is also the best conductor of heat. These two facts suggest it would be excellent for tiny circuits where electrical fields and currents can be quite high and lots of heat can be generated in small regions.

If LEDs could be built, the excellent optical properties of diamond (highest optical density and excellent transparency) could be useful for manipulating light in electro-optical circuits.


 

Offline evan_au

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Re: Has anyone experimented with diamond as a semiconductor?
« Reply #1 on: 22/01/2013 09:13:17 »
One of the key parameters for a semiconductor is the bandgap: If it is too small, the material will be a conductor at room temperature; if it is too large, it will be an insulator at room temperature.

Diamond has a bandgap of 5.5 eV (far higher than Silicon at 1.1 eV and Gallium Arsenide at 1.5 eV), which effectively makes it an insulator, despite normal levels of doping.
See http://en.wikipedia.org/wiki/Band_gap#List_of_band_gaps

However, diamond does have excellent physical characteristics, which might be useful for a Venus rover, for example. At the temperatures on the surface of Venus, diamond might be a useful semiconductor (but testing it on Earth would be rather tricky).

Similarly, diamond might be useful for electronics operating deep under Earths surface, or electronics operating inside a jet engine - but don't expect it to do anything useful until it warms up.

Diamond has been investigated for use as a memory store in a quantum computer - an exotic application for an exotic material!
http://en.wikipedia.org/wiki/Quantum_computer#Developments
« Last Edit: 22/01/2013 09:26:05 by evan_au »
 

Offline AndroidNeox

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Re: Has anyone experimented with diamond as a semiconductor?
« Reply #2 on: 23/01/2013 20:05:48 »
evan, thank you for the reply. That's exactly what I wanted to know.

I can see that diamond would probably be less efficient than silicon. The higher energy (voltage) required to push electrons (& holes) across junctions would make for much higher heat generation per charge carrier.
« Last Edit: 23/01/2013 21:35:42 by AndroidNeox »
 

Offline Bored chemist

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Re: Has anyone experimented with diamond as a semiconductor?
« Reply #3 on: 23/01/2013 21:32:17 »
http://www.sciencemag.org/content/292/5523/1899

Probably not written by researchers from Venus.

 

Offline CliffordK

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Re: Has anyone experimented with diamond as a semiconductor?
« Reply #4 on: 24/01/2013 02:07:57 »
Is it possible to manufacture flawless diamonds yet?

I thought the best quality diamonds were still natural diamonds.  And, most of them have slight impurities (causing color). 

If one needs a polished crystal, the diamonds can give a very high quality surface. 

I would hate to imagine the cost if one needed large sheets of flawless diamond, perhaps 1 square cm.
 

Offline CliffordK

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Offline evan_au

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Re: Has anyone experimented with diamond as a semiconductor?
« Reply #6 on: 31/01/2013 19:12:27 »
"Flawless" natural diamonds means that you cannot see any bubbles, cracks or pieces of embedded grit under a 10x magnification jeweler's loupe (ie the human eye can't see any problems in a gem). http://en.wikipedia.org/wiki/Diamond_clarity

On the other hand, producing high-performance semiconductors requires atomic-scale purity in a single crystal, at the level only visible under an electron microscope or atomic-force microscope. Semiconductors could take advantage of diamond's very high electron mobility, under the right conditions. (An ultraviolet LED/laser or solar cell is a natural product of diamond's very large bandgap - if you can get it to conduct at all.)

Diamond is currently used as a high-quality electrical insulator, and high-grade heatsink in semiconductors, plus artificial gems - multiple crystals are acceptable for these applications.   
Chemical vapor deposition has made a big difference to all these applications.
http://en.wikipedia.org/wiki/Chemical_vapor_deposition#Diamond
« Last Edit: 31/01/2013 20:03:52 by evan_au »
 

Offline CliffordK

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Re: Has anyone experimented with diamond as a semiconductor?
« Reply #7 on: 31/01/2013 19:49:08 »
Chemical vapor deposition has made a big difference to all these applications.
http://en.wikipedia.org/wiki/Chemical_vapor_deposition#Diamond

I didn't realize chemical vapor deposition was being used for diamonds now.  I thought it was all high pressure/temperature. 

Nonetheless, if the Wikipedia photo is representative of the quality of the synthetic CVD diamonds, then there is additional work necessary for production of better quality than the natural diamonds.


click for more sizes


Semiconductors could take advantage of diamond's very high electron mobility, under the right conditions.

I thought graphite had high electron mobility due to the benzine ring structure.  However, diamond has all electrons shared in the 3 dimensional tetrahedral shape, and thus much lower electron mobility.

Here's an interesting article about The New Diamond Age, including using boron doped synthetic diamonds as semiconductors. 

Low resolution YouTube film about CVD diamonds.
« Last Edit: 31/01/2013 20:02:56 by CliffordK »
 

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Re: Has anyone experimented with diamond as a semiconductor?
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