Why depletion layer width at the collector junction are more than the depletion layer width at the emitter junction?

The depletion layer width at the collector junction is typically wider than that at the emitter junction due to the differences in doping concentrations. The collector region is generally lightly doped compared to the heavily doped emitter region, resulting in a larger electric field and a broader depletion region. Additionally, the collector junction must accommodate a higher reverse bias, which further expands the depletion region to maintain charge neutrality and facilitate efficient charge separation.