Let's consider a PN junction which is at zero biased voltage. Once the junction is formed charges are diffused across the junction and form the depletion region and stops further diffusion. So no further diffusion takes place. But due to the created electric field minority carriers can drift across the depletion layer creating a drift current. Thing that cant understand, if diffusion has stopped after the depletion layer is formed, how come drift and diffusion current get equal. Is that because even the depletion layer is already formed diffusion contentiously occurs keeping depletion layer intact or same size? Can someone explain this scenario?
You answered it yourself. When the depletion region begins to widen, diffusion current decreases, but doesn't cease. Simultaneously drift current comes into picture due to electric field. At equillibrium, the value of depletion current and drift current becomes equal, hence the depletion region does not grow/shrink further.