The diffusion current in p-n junction is
1
From the p-side to the n-side
2
From n-side to the p-side
3
From the n-side to the p-side if the junction is forward biased and in the opposite direction if it is reverse-biased.
4
From the p-side to the n-side if the junction is forward biased and in the opposite direction if it is reverse biased.