Is 3004M1C a photodiode or a phototransistor?

Question

The datasheet describes the 3004M1C as a "high speed and high sensitive PIN photodiode". Distributors also label it as a photodiode. However, the datasheet mentions "Collector-Emitter Breakdown Voltage", "Emitter-Collector Breakdown Voltage", "Collector-Emitter Saturation Voltage", which seems to make sense only for phototransistors. I also tried some checks suggested in "is it a photodiode or a phototransistor?": The open circuit voltage of the 3004M1C is 0 when I point a bright light to it. Also, the diode tester doesn't read anything.

So, is the 3004M1C a phototransistor mislabeled as a photodiode?

Answer 1

TLDR: Data sheet is not to be trusted.

• Page 1 describes a photodiode with words only.
• Page 2 refers to the device as a "LED"
• Page 2 suggests it is made of Silicon (no LEDs are made of silicon), but photodiodes and phototransistors are mostly silicon-based.
• Page 3 tells of specifications for a phototransistor, not a photodiode.
• Page 4,5 describes specifications compatible with a photodiode

Perhaps HUIYUAN collated these datasheet pages incorrectly, incorporating page 3 from some other source. Pages describing a "photodiode" outnumber pages describing something else. But voting in this case is a dubious metric.

Maybe suitable for hobby purposes.
The test of measuring open circuit voltage is a satisfying one to me, for a two-terminal photodiode device. Use a voltmeter having high internal resistance. For example, many digital multimeters have 10 Mohms input resistance, whereas analog multimeters have far less, perhaps as low as 10kohms.

Illuminated by sunlight, or light from an incandescent lamp at close range, you should see some DC voltage, but no more than about 0.6V. The more positive terminal is the photodiode anode.
Be aware that this test will not discriminate a LED from a photodiode - both LEDs and photodiodes can convert light to photocurrent.

Answer 2

The manufacturer is an LED assembler. They don't make LED chips, let alone photodiode chips, but rather buy them from a semiconductor fab (probably in the form of a wafer scribed and on a stretchy backing) and stick them into packages in job lots.

The 5mm variant is shown on their website, with a similar sketchy datasheet.

I have grave doubts as to how well they are tested or if they are properly characterized, but I don't doubt that they are selling some form of generic photodiode or phototransistor chip packaged into one of their standard LED moldings. The relatively high sensitivity and relatively low speed suggests a phototransistor. Compare the Kingbright phototransistor datasheet (and note that the speed of 15usec is with a 10x higher load resistance than the Huiyuan part, so essentially the same).

As others have said, it's not really worth bothering with this kind of supplier in low quantities. If you have an application that uses something like this in large quantity they'll prepare a multi-page specification document that covers exactly how they will test and characterize the parts, and provide samples. But they're not going to bother with that for a small order.

Here's a similar 3mm⌀ product from Chau Light that's less than 3 cents in quantity and has a better datasheet. There are other similar suppliers.