What exactly is difference between diffusion current and drift current?
Drift is when electrons move in response to the electric field from an applied voltage source. Diffusion is when electrons move in response to the electric field from other electrons/holes in the semiconductor.
Drift is due to an applied force while diffusion is only because of the concentration gradient of particles. Particles move from the region with high concentration to anywhere with lower concentration with no force.
Diffusion is not in response to any electric filed. It is only caused by concentration gradient.
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