TITLE: What causes reverse leakage current in an LED?
QUESTION [1 upvotes]: I've read it can be due to 'intrinsic semiconductor conduction' and surface conduction. The LED I am looking at is InAs, which is apparently prone to surface conduction. I have tried out what these two quantities are on google but have been unsuccessful. In particular because I have no extensive mathematical knowledge of the subject, and so am looking for a qualitative answer. 
And why does reverse leakage current increase with higher temperatures?

REPLY [1 votes]: As Horta answered, there are a few pathways for current leakage in a classical pn junction. Both phonon and photon generated carriers contribute to leakage current.
 Look up the derivation of the ideal diode equation. Forward bias current is due to diffusion, the exponential term. Reverse bias current , the constant term, is due to drift of generated carriers by the built in field of the junction. At equilibrium, they balance.
The key here is the word "ideal". If that equation held everywhere, you could bias to negative infinity with no additional current.  Other processes occur at high reverse field. These include Zener tunneling, defect assisted tunnelling, Avalanche breakdown, and dielectric breakdown. They all contribute at some point, and will cause "leakage" current. These processes aren't included in the ideal diode equation!
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