Point contact diodes and transistors are said to be formed through discharging a high current through either tungsten or phosphorus-bronze wire in contact with an n-type slab of germanium, forming a thin p-type region by the area of the wire contacting it.

I was wondering the mechanism for the p-type formation? Is it that the tungsten from the wire or tin contained in phosphorus-bronze is acting as a p-type dopant? Is there crystal damage leading to point defects acting as p-type acceptors?

I tried looking for a good answer but can't find one. The early works on the topic did not understand the mechanism well enough, and the later works don't reflect upon it.

Thanks for the input.