如果集电极电压继续下降，集电极会进一步正偏，产生比较明显的电流（扩散电流）。因此大量的电洞（空穴）必须被补充到基极（基极与集电极有正偏的漂移电流，新增的基极电流），好像β减小。
换而言之，重度饱和导致基极电流急剧上升，因此β快速下降。
For VCE = VBE, the junction sustains a zero voltage difference, but its
depletion region still absorbs most of the electrons injected by the emitter into the base.
哈哈，还是有点不一样。
For VCE = VBE, the junction sustains a zero voltage difference, but its
depletion region still absorbs most of the electrons injected by the emitter into the
base.
楼主
。第五版记得有中文版PDF下载，不过清晰度差点……
