All About Circuits > Volume III > 3.12.5 Photo diodes

Thread Starter


Joined Dec 12, 2015
Not quite sure of the intent of the sentence:

Light entering the top of the photodiode stack fall off exponentially in with depth of the silicon.

But this may be correct:

The intensity of the light entering the top of the photodiode stack falls off exponentially as a function of depth.

Hasan Yahya

Joined Nov 10, 2015
I just highlight the grammar of the text "stack falls off" consisting of two verbs. According to grammar If two verbs in a queue, the second verb must have added with "to" as preposition. So "stack falls off " should be written as " stack to fall off ". Is it useful ?


Joined Mar 31, 2012
I'm most certainly NOT a grammar expert, but is "off" really a verb here? Or perhaps I would be better served stepping back and asking what are the two verbs in question here? It certainly isn't "stack", since that is clearly a noun.

If using "stack to fall off" then the sentence is makes little sense because it doesn't give any indication of what is causing it to fall off. You would need to write something like:

"Proportional absorption of light as it passes through causes the intensity in the photodiode stack to fall of exponentially as a function of depth."

I had to force things in order to use the exact phrase you recommend and I think I probably committed some other grammar sin in doing so.

I see the basic sentence being, "The intensity falls off exponentially."

What falls off exponentially? The intensity of the light.

What light? The light entering the photodiode stack.

Exponential with respect to what? With respect to depth within the stack.

So to address all of those questions in one sentence, I think the recommended sentence works well.