low-cost sensitive silicon photodiodes.

[Winfield Hill]

What's a good source for high-quality large-area (0.5" dia, 1cm^2,
etc.) silicon photodiodes, meant for use at very low light levels?
One other spec, it must be inexpensive, say no more than $5 each.
The UDT parts I've been using work well, but cost about $50 each.

 

[Phil Hobbs]

What's a good source for high-quality large-area (0.5" dia, 1cm^2,
etc.) silicon photodiodes, meant for use at very low light levels?
One other spec, it must be inexpensive, say no more than $5 each.
The UDT parts I've been using work well, but cost about $50 each.

Win,

How low is low? Do you need PIN or is PN okay?

You can often come out ahead by tiling with solar cells--the dark noise goes
up as the area while the signal goes as area**2, and you can't beat the
price. Depends on the BW, of course.

Cheers,

Phil Hobbs

 

[John Popelish]

What's a good source for high-quality large-area (0.5" dia, 1cm^2,
etc.) silicon photodiodes, meant for use at very low light levels?
One other spec, it must be inexpensive, say no more than $5 each.
The UDT parts I've been using work well, but cost about $50 each.

These are a bit lower cost than $50:
$28 ea. from Digikey:
http://www.photonicdetectors.com/pdf/pdbc615.pdf

$14.34 ea.
http://www.photonicdetectors.com/pdf/pdbc613.pdf

These are better (lower dark current), but they just raised the price:
http://www.photonicdetectors.com/pdf/pdbv110.pdf


If you need just a few, not a reliable source, you might take a look
at the surplus stuff at Electronic Goldmine, like:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G13585&variation=&aitem=8&mitem=59
http://www.goldmine-elec-products.com/prodinfo.asp?number=G13644A&variation=&aitem=3&mitem=15
http://www.goldmine-elec-products.com/prodinfo.asp?number=G13556&variation=&aitem=7&mitem=59

 

[Tony Williams]

What's a good source for high-quality large-area (0.5" dia,
1cm^2, etc.) silicon photodiodes, meant for use at very low
light levels? One other spec, it must be inexpensive, say no
more than $5 each. The UDT parts I've been using work well, but
cost about $50 each.

Silonex do large-area planar photodiode elements.

Or a collimating lens onto an ordinary photodiode.

 

[Mike Harrison]

What's a good source for high-quality large-area (0.5" dia, 1cm^2,
etc.) silicon photodiodes, meant for use at very low light levels?
One other spec, it must be inexpensive, say no more than $5 each.
The UDT parts I've been using work well, but cost about $50 each.

Large-area diodes will never be cheap, as they are relatively specialist, and have an inherently
large silicon area and hence manufacturing cost. A lens plus a smaller diode will probably be
cheaper if your application allows.

 

[Johnson]

Don't forget that as the area increases, the junction capacitance also goes
up making the devices a little tricky to keep stable. Burr Brown (TI) has
some application notes on this -- why not try one of their amplifer
incorporated diodes? I have also used the Texas Advanced Optical "light to
frequency" converters -- these obviate the need of an ADC -- just count the
pulse width. (It helps to shape the pulse a bit, however.)

 

[Robert Baer]

What's a good source for high-quality large-area (0.5" dia, 1cm^2,
etc.) silicon photodiodes, meant for use at very low light levels?
One other spec, it must be inexpensive, say no more than $5 each.
The UDT parts I've been using work well, but cost about $50 each.

Give me your address, and i will send one or two of the old Fairchild
FPT 100s; they were transistors *designed* to be used as photodetectors.
None of the industry standard flim-flam of putting a glass lens at
the top of a metal canned 2N2222.
Now all i gotta do is find them!

 

[Kryten]

I recall this 100 mm^2 device from the RS catalogue:

http://rswww.com/cgi-bin/bv/rswww/subRangeAction.do?catoid=-1600782374&cacheID=ukie

But it is 149 UKP(!)

Even allowing for RS expensiveness, I bet they are not cheap from other
places either. :-<

Sounds like there's the common conflict of needing high quality and low
price.

I'd suggest el-cheapo solar cells, but I guess they won't be that good.

What's the application?

 

[Kryten]

http://rswww.com/cgi-bin/bv/rswww/subRangeAction.do?catoid=-1600782346&cacheID=ukie

Only 85 UKP, but still too dear.

 

[Don Foreman]

What's a good source for high-quality large-area (0.5" dia, 1cm^2,
etc.) silicon photodiodes, meant for use at very low light levels?
One other spec, it must be inexpensive, say no more than $5 each.
The UDT parts I've been using work well, but cost about $50 each.

Speed requirement?

Quantum efficiency doesn't vary that much among silicon diodes. The
more limiting variable is dark current. Larger diodes may or may not
be more sensitive, because dark current may increase as much as
photocurrent for given radiant power density or luminous flux density.
If speed and/or bandwidth is an issue, then noise or D* is also
important.

I've used photodiodes with 1 mm^2 die under starlight condx. They
were made by Fairchild back in the '70's, weren't very expensive.

 

[John Popelish]

What's a good source for high-quality large-area (0.5" dia, 1cm^2,
etc.) silicon photodiodes, meant for use at very low light levels?
One other spec, it must be inexpensive, say no more than $5 each.
The UDT parts I've been using work well, but cost about $50 each.

I forgot about these.

If you can tile an area with several smaller diodes and parallel them,
these are hard to beat for cost to performance ratio. About $1 each,
with 7 mm^2 area and dark current around a nA at room temperature with
10 V reverse bias.
http://rocky.digikey.com/WebLib/Osram/Web Data/bpw34_spdf.pdf

 

[Uwe Bonnes]

What's a good source for high-quality large-area (0.5" dia, 1cm^2,
etc.) silicon photodiodes, meant for use at very low light levels?
One other spec, it must be inexpensive, say no more than $5 each.
The UDT parts I've been using work well, but cost about $50 each.

Did you really calculate what you gain by a larger area photodiode with
higher leakage currents against a feedback resistor with higher value and an
amplifier with lower Bias?

 

[John Devereux]

Did you really calculate what you gain by a larger area photodiode with
higher leakage currents against a feedback resistor with higher value and an
amplifier with lower Bias?

If the photodiode is operated at zero bias, does the leakage not go to
zero?

.. .---R---.
.. | |
.. | |\ |
.. .------+--|-\__|_____
.. | .---|+/
.. v | |/
.. - |
.. |PD |
.. -+-----+-----------------


I think Tony already mentioned Silonex, these were the lowest cost
that I found, too. They make large area "bare" photodiodes (look like
solar cells) as well as the lowest cost "packaged" diodes I found.