What is the energy conversion in a forward biased silicon diode?

[MHD93]

A typical silicon diode has potential difference of 0.7V when forward biased, to what kind of energy is the (0.7V)*(I)*($\Delta$t) converted? thermal energy only? isn't there potential energy through the electric field in the pn junction?

 

[mfb]

Unless you have an LED, the energy is released mainly as heat.

isn't there potential energy through the electric field in the pn junction?

For every electron, sure. And if electrons cross the junction, they release this energy.

 

[MHD93]

And if electrons cross the junction, they release this energy.

If this potential energy were released into kinetic, then there's no net change in electrons' energy across the diode, and therefore $\Delta$V is zero not 0.7V. what's wrong?

 

[mfb]

Kinetic energy of what?
Electrons are not free in the metal, they cannot just get kinetic energy and "fly in some direction".
Even then, their potential energy would change, and you have a voltage difference.