# Depletion region- diode

## Main Question or Discussion Point

At depletion layer of p region, there more negative ions thus negatively charged region.
Likewise at n region, it is positively charged.

Then why in equivalent forward bias the diode behave as a battery of .7v with positive at depletion region of the p region where it is negatively charged?

## Answers and Replies

Related Electrical Engineering News on Phys.org
Diode never behaves like a battery.

I'm reading Electronic Devices by Floyd 7edition page31- Diode Models.

In a forward bias, the complete diode model is depicted as a 0.7V battery with + polarity facing the + Vbias , a resistor and a switch all in series.

In reverse bias, only a switch which is connected parallel to a resistor.

Its an approximate model of a diode. Even below 0.7V the diode current is not zero in reality. But that current is very low and can be ignored. The model has 0.7V battery so that at 0.7V the current becomes zero and increases linearly onward. This is not a physical phenomena.

http://img829.imageshack.us/img829/9049/new2qm.jpg [Broken]

My question is why is it that it has positive polarity even though the depletion layer of p region is negatively charged.
To my assumption it should be negative polarity.

Last edited by a moderator: