Question

who can define diode construction and working completely that i can understand it completely

Answer 1

CONSTRUCTION:-
when a P-type semiconductor is placed in contact with N-type semiconductor, an assembly so obtained is called P-N type semiconductor diode.

When P & N type semiconductors are kept in contact, holes and electrons migrate to the N & P section respectively and neutralise each other. As a result a thin layer at the juction becomes devoide of charge carriers, called Depletion layer.

WORKING (forward bias):-
When P & N sections of a semiconductor diode are connected to positive and negative terminals of a battery rspectively is called forward bias. The holes of P-section and electrons in N section are repelled by positive and negative terminals of the external source to the depletion layer. The thickness of the layer decreases, the resistance also decreases and the semiconductor conducts.

Answer 2

best method to learn diode principle is grab a diode and put it in to a practical circuit and inspect each values carefully...best measurement instrument will be oscilloscope.. try XY mode for detailed characteristic curve