| abstract |
A method of making bipolar semiconductors in which the base contact regions and the emitter region are defined by one masking step. A layer of polycrystalline silicon is formed on a substrate, the polycrystalline layer being removed at the positions for the base contact regions and the emitter produced beneath the remaining part of the layer by diffusion from the polycrystalline silicon which has been doped with a suitable emitter region dopant. |