Can anyone explain the zero bias dark current observations in this paper?

[Devin-M]

I’ve been trying to understand the conclusions in this paper for a long time…

https://apps.dtic.mil/sti/tr/pdf/ADA429637.pdf

It seems it was published in Optical Engineering, Vol 38, No. 8, August 1999.

I thought if we have a photodetector with no light shining on it and no outside voltage applied to the terminals from an external source, ie “no bias voltage” then we shouldn’t measure any current from the device.

Specifically I am asking about the statement on page 1428, first sentence of last paragraph…

“In this study, we have attempted to explain the presence of a large nonzero dark current when the applied bias voltage is zero”

Where is the power coming from to produce this current if there is no external voltage applied and no light shining on the device?

 

[bob012345]

“In this study, we have attempted to explain the presence of a large nonzero dark current when the applied bias voltage is zero”

Where is the power coming from to produce this current if there is no external voltage applied and no light shining on the device?

First, they are talking miniscule amounts of current. Then, the effect occurs at very low temperature <50K. They attempt to explain it by a dynamic tunnelling process. They seem to suggest "trap-assisted and Fowler-Nordheim tunneling, which dominate at lower temperatures" as where the source of this tiny amount of energy comes. I would ask, is the entire circuit below 50K or just a part of it?

 

[Lord Jestocost]

"In any case, a dark current can normally not occur for operation with zero bias voltage, since there is no energy supply available for it – at least as long as the temperature of the device is uniform, excluding any Peltier effects."

from https://www.rp-photonics.com/dark_current.html

 

[Fred Wright]

IMO (for what it's worth) the author's explanation of zero bias tunneling anomalies is incomplete. I think a better explanation can be derived from the paper Surface magnetism of gallium arsenide nanofilms. From the abstract:
"Gallium arsenide (GaAs) is the most widely used second-generation semiconductor with a direct band gap, and it is being increasingly used as nanofilms. However, the magnetic properties of GaAs nanofilms have never been studied. Here we find by comprehensive density-functional-theory calculations that GaAs nanofilms cleaved along the ⟨111⟩ and ⟨100⟩ directions become intrinsically metallic films with strong surface magnetism and the magnetoelectric effect. Surface magnetism and electrical conductivity are realized via a combined effect of charge transfer induced by spontaneous electric polarization through the film thickness and spin-polarized surface states."
I infer from this paper that a normally applied infrared electric field can produce a tunneling current in an unbiased tunnel junction.

 

[bob012345]

I infer from this paper that a normally applied infrared electric field can produce a tunneling current in an unbiased tunnel junction.

And was there such an applied field in the original paper the OP mentioned?

 

[Devin-M]

They seem to suggest "trap-assisted and Fowler-Nordheim tunneling, which dominate at lower temperatures" as where the source of this tiny amount of energy comes.

I looked up Fowler-Nordheim tunneling and found the effect is used by applying voltage to erase flash memory but in this case no external voltage is being applied.