[SI-LIST] Re: si-list Digest V5 #210

Jut to clarify things I would like to ask a question:

My understanding was that pure silicon is not conductive,
not even at room temperature(?).  The doping is what
freezes up some electrons to make it conductive.  How
does this relate to temperature?

Thanks,

Arpad
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of Daniel Chow
Sent: Monday, May 16, 2005 10:44 AM
To: John Zasio
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: si-list Digest V5 #210

My bad.

My statement was true for pure silicon.

Heavy doping significantly changes the properties of silicon.



-----Original Message-----
From: John Zasio [mailto:zasio@xxxxxxxxxxxxxxxxxxx]=3D20
Sent: Monday, May 16, 2005 10:25 AM
To: Daniel Chow
Cc: si-list@xxxxxxxxxxxxx
Subject: Re: [SI-LIST] Re: si-list Digest V5 #210

Daniel,

Silicon devices do work and work well at liquid nitrogen =
temperatures.=3D20
CMOS devices will run at two to three times faster than at room
temperature.

In the mid 80s ETA Systems shipped a CMOS Supercomputer cooled by liquid

nitrogen. Although the product was not a commercial success, the=3D20
technology worked very well.

John Zasio

Daniel Chow wrote:

>Jon,
>
>No silicon part will work at liquid nitrogen temperatures (77 Kelvin).
>
>Silicon is an insulator at that temperature.  The charge carriers are =
=3D
=3D3D
>"frozen out" at low temperatures.
>
>Please refer to Chapter 8 of "Solid State Physics" by Charles Kittel
for =3D3D
>more details.
>
>Thanks!
>=3D3DA0
>=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D=
3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D=3D
3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D
>Daniel Chow, Ph.D.
>Sr. Product Engineer
>ALTERA
>Office: (408) 544-8100
>Fax: (408) 544-7602
>Email: dchow@xxxxxxxxxx
>=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D=
3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D=3D
3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D=3D3D3D
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx
>[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Jon Keeble
>Sent: Sunday, May 15, 2005 11:56 PM
>To: si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Low Temperature Limit
>
>
>On this list, all signals are analog. So, hereabouts, what do you call
a
>signal that is actually .. analog?
>
>First question (a bit off topic for this group): what determines the =
=3D
=3D3D
>lower
>operating temperature of a silicon circuit? For instance, TI specifies
=3D3D
>the
>OPA2134 opamp from -55C to 125C. Is -55C as cold as it seems reasonable
=3D3D
>to
>measure, and the part will work down to liquid nitrogen? or does =3D3D
>something
>stop working.
>
>Second question: why don't vendors specify noise / jitter as a function
=3D3D
>of
>temperature? A brief reading in the ieee electron devices department
>indicates that drain noise and other 'excess' noise in FETs is '4kT' =
=3D
=3D3D
>style
>noise.
>
>These questions came up in the low frequency analog domain, but maybe
>relevant in Gbit circuits (?).
>
>Regards
>
>Jon Keeble
>
>
>
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>
>
> =3D20
>


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