Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: SiliconTears on 23/01/2019 04:57:14

Title: How can you tell silicon from germanium non-destructively?
Post by: SiliconTears on 23/01/2019 04:57:14

Hi there,

Is there a (non-destructive) way to tell the difference between Silicon and Germanium (or Antimony and Arsenic for that matter) simply by looking at it (either with naked eye or some sort of equipment)?

Could a Geologist or even a Jeweller tell that a particular stone was Silicon just by looking at it?

Thank you for your time

Regards
ST

Title: Re: How can you tell silicon from germanium non-destructively?
Post by: chiralSPO on 23/01/2019 05:06:02

Silicon and germanium do have a very similar luster, but germanium is more than twice as dense (5.3 g/mL vs 2.3 g/mL) it would be very easy to tell the difference between the two just by picking them up (for anything larger than a lima bean), and trivial to distinguish smaller pieces using an analytical balance and a small graduated cylinder.

One could even put a sample in a vial containing diiodomethane (density of 3.3 g/mL). If it floats, it's silicon, if it sinks, it's germanium (assuming you know it is one of the two).

Title: Re: How can you tell silicon from germanium non-destructively?
Post by: SiliconTears on 23/01/2019 05:09:07

Thank you chiralSPO

That has helped me immensely!

Thank you so very very much

Title: Re: How can you tell silicon from germanium non-destructively?
Post by: chiralSPO on 23/01/2019 05:10:02

Glad to be of service! (note: I edited my last post, to add a bit about diiodomethane, which may also be of use)

Title: Re: How can you tell silicon from germanium non-destructively?
Post by: SiliconTears on 23/01/2019 05:19:49

I saw the edit, thank you! I am so chuffed with your clever answers, thank you chiralSPO! :)

Title: Re: How can you tell silicon from germanium non-destructively?
Post by: evan_au on 23/01/2019 09:47:42

The two elements have a different band-gap (https://en.wikipedia.org/wiki/List_of_semiconductor_materials#Table_of_semiconductor_materials) (Si 1.1V, Ge 0.7V), which means that they will absorb light of different wavelengths.
- The lustre is in the visible band
- But they become transparent at different wavelengths in the infra-red band

They also have a different refractive index (https://en.wikipedia.org/wiki/List_of_refractive_indices).

If it is in the form of a semiconductor device, the forward voltage drop of germanium is lower than that for silicon (all other things being equal), as a result of the difference in bandgap.

Silicon is used more often than germanium in today's mass-production semiconductors as it is able to operate at higher temperatures with lower leakage currents.

Title: Re: How can you tell silicon from germanium non-destructively?
Post by: SiliconTears on 24/01/2019 06:10:38

Hi evan_au

I saw your post this morning and I've been reading about the band gap and refractive index you've linked, it's fascinating, thank you very much!

Thank you
ST

Title: Re: How can you tell silicon from germanium non destructively
Post by: Colin2B on 31/01/2019 17:46:27

Quote from: TimothyKiz on 31/01/2019 17:28:13

how can you tell the real entities from entities you make with energy in astral?
how do you tell anything natural from something you create in astral?

Your post does not seem to be related to the question asked in this thread.
Please make your post relevant or it will be removed
Thank you