we know that due to diffusion current their exists a electric field and hence barrier potential.but when voltmeter is applied it reads zero it means that their exists some force which this zero.May I know which force this may be? If we say no then it violates law of conservation of energy

 

Drift current implies an electric field. Diffusion current does not. Diffusion current is sort of like Brownian motion for charge carriers. Sort of.

 

but during fabrication due diffusion of charge carriers their forms a uncovered ions which result in electric field. not nesserially due drift current

 

I'm sorry, I do not understand the syntax of the last post. Could you re-translate?