| 摘要 |
<p>1. A power transistor with open circuit voltage holding properties obtained by the stages consisting of : starting with a substrate (10) with a first kind of conductivity having a high dopage level ; epitaxially forming an intermediate zone (20) with the first kind of conductivity ; by epitaxially forming a collector layer (30) with the first kind of conductivity and a low dopage level, then forming a base layer (40) with the second king of conductivity, then an emitter layer (50) with the first kind of conductivity, characterized in that the intermediate zone (20) has a substantially constant concentration gradient in its thickness equal to 20 to 40 mu m per ten-fold concentration difference, the concentration of this intermediate zone being equal to that of the collector layer at the level of this layer and increasing towards the substrate, the thickness of the intermediate zone being such that the concentration of doping agent decreases by about at least a factor of ten across the thickness of this zone.</p> |
