In "Principles of transistor circuits, 8th edition" (top of p26) it is said that once holes have been injected in the base region by a forward biased base-emitter junction (which I understand) of a PNP transistor, they diffuse towards the collector and are then swept across.
However, I thought the collector-base junction was reverse biased which means that the electric field created by the external bias adds to the potential barrier? How is it that holes spontaneously cross this huge potential barrier?
Edit after the answers: After drawing a diagram it is much clearer. The potential barrier creates a field reinforced by the reverse bias, but that field goes against holes going towards the base - it's actually accelerating holes from the base to the collector.