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From: Tim Williams on 11 Aug 2010 19:56
"Phil Hobbs" <pcdhSpamMeSenseless(a)electrooptical.net> wrote in message
news:4C631E7B.6070908(a)electrooptical.net...
> Do you have a reference for the PFET performance vs bandgap? InGaAs has
> a much lower bandgap than GaAs, but its hole mobility is similar.

Not performance directly, but it all comes back to mobility, and it's well
known that holes move slower, especially in higher bandgap materials. A
scatterplot could be interesting, but I don't have a big table of
semiconductors (especially all those funky compound semis like CdTe,
etc.).

I'm basing my assertion on the one semiconductor physics class we had,
which used the textbook, _Solid State Electronic Devices_, 6th ed.,
Streetman and Banerjee, Pearson Prentice Hall (2006). There's a table in
Appendix 3 (p.540) that lists bandgap, electron and hole mobilities, and
some other things, for a number of semiconductors.
http://myweb.msoe.edu/williamstm/Images/Semiconductor_Properties.png
Ah, thanks for challenging my assertion. It looks more correlated with
direct vs. indirect, not bandgap energy. In fact, some very crummy (at
room temperature) low-bandgap materials have quite high mobility,
especially those with indium (InSb has the lowest bandgap and the highest
mobility). One material even has higher P-mobility (AlSb), another is
equal (PbSe).

Chemistry is like politics. Generalizations don't work...

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms


From: Jamie on 11 Aug 2010 20:48
markp wrote:

> "markp" <map.nospam(a)f2s.com> wrote in message
> news:8cgqjoFqhU1(a)mid.individual.net...
>
>>"Tim Williams" <tmoranwms(a)charter.net> wrote in message
>>news:nhE8o.64614$4B7.49357(a)newsfe16.iad...
>>
>>>"markp" <map.nospam(a)f2s.com> wrote in message
>>>news:8cgekjFubtU1(a)mid.individual.net...
>>>
>>>>You mean PMOS as in P-channel MOSFET? Is that enhancement mode? There
>>>>are certainly quite a few P channel enhancement mode MOSFETs around, I
>>>>tend to
>>>>use the BSS84 as a P-channel equivalent of the 2N7002. They are pretty
>>>>close
>>>>in price, certainly not significantly more, and multi-sourced.
>>>
>>>I didn't see BSS84 on Mouser's search. Ha, figures, the cheapest entry
>>>doesn't have any characteristics:
>>>http://www.mouser.com/ProductDetail/NXP-Semiconductors/BSS84215/?qs=sGAEpiMZZMutXGli8Ay4kDE4J8KCiPsFBEpkUtYt8m4%3d
>>>Still 11 cents in 100s, whereas 2N7002s (that show up in the list) are
>>>5c. Not "significantly" more, but it's over a factor of two anyway.
>>>
>>>I suppose I could try arguing "multi-source" as well, since there's only
>>>a few that are near that price range AND in stock (to bend the meaning of
>>>"source" to mean "cheapest parts only"..). Sure, there are lots in
>>>stock, but they seem to average $0.30 in hundreds, which is just silly
>>>for an SOT-23.
>>>
>>>Tim
>>>
>>
>>You can get BSS84 for somewhat less than 11c:
>>http://gb.mouser.com/Search/Refine.aspx?Keyword=BSS84
>>BSS84LT1G showing as 4.3p (UK prices) for 100 off.
>>
>>Also in Newark (www.newark.com) Fairchild BSS84 going for 6c for 100 off.
>>NXP version for 11c.
>>
>>Mark.
>>
>
>
> Oops, some of those not in stock. This always happens when we come out of
> recession. The reason for non-stock is allocation problems, the prices of
> anything left in stock might go up accordingly. Still it looks like BSS84 is
> roughly the same as 2N7002 if they were.
>
> Mark.
>
>

"Come out of recession" ?


From: Robert Baer on 12 Aug 2010 04:41
Daku wrote:
> Could some electronics guru provides some URLs for authentic buffered
> FET logic and/or direct coupled FET logic ? Thanks in advance.
Isn't CMOS logic FETs??
From: Michael A. Terrell on 12 Aug 2010 12:54

Robert Baer wrote:
>
> Daku wrote:
> > Could some electronics guru provides some URLs for authentic buffered
> > FET logic and/or direct coupled FET logic ? Thanks in advance.
> Isn't CMOS logic FETs??


FETs and anti-FETs. ;-)
From: Robert Baer on 13 Aug 2010 04:26
Michael A. Terrell wrote:
> Robert Baer wrote:
>> Daku wrote:
>>> Could some electronics guru provides some URLs for authentic buffered
>>> FET logic and/or direct coupled FET logic ? Thanks in advance.
>> Isn't CMOS logic FETs??
>
>
> FETs and anti-FETs. ;-)
Does uncle FETster of the Adams family count?
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