Semiconductor device having rapid removal of majority carriers from an active base region thereof at device turn-off and method of fabricating this device

A semiconductor device exhibiting rapid removal of majority carriers from an active base region thereof during turn-off of the device, comprising:

• (a) a semiconductor substrate comprised of first and second adjacent regions, said first region being doped to one conductivity type and said second region being doped to the opposite conductivity type, at least a major portion of said first region adjacent said second region being doped to a first concentration of at least 5.times.10.sup.17 dopant atoms per cubic centimeter, said second region being doped to a second concentration at least as high as said first concentration;
• (b) a semiconductor layer disposed on said substrate and forming a first interface therewith and comprising at least third and fourth regions;
• (c) said second region extending to said first interface and having a configuration whereby for selected cross sections through said device perpendicular to said first interface, segments of said first and second regions alternate along said first interface;
• (d) said layer third region comprising said active base region and separating said substrate from said layer fourth region, said third region being doped to said opposite conductivity type and said fourth region being doped to said one conductivity type, at least a major portion of said third region being doped to a third concentration substantially lower than said frist concentration, a major portion of said fourth region being doped to a fourth concentration substantially higher than said third concentration, said third and fourth regions having a second interface therebetween, said second interface being substantially in a single plane extending through said layer over an area which is sufficient to span at least two of said second region segments situated along a given one of said selected cross-sections;
• (e) a first main electrode ohmically connected to a surface of said first region of said substrate, not ohmically connected to said second region and spaced from said second region;
• (f) a second main electrode electrically connected to at least a surface of said fourth region;
• and
• (g) a gate electrode contiguous with said fourth region, said gate electrode, when an appropriate main bias is applied between said first and second main electrodes, being responsive to an appropriately applied gate bias to render said device conductive between said first and second main electrodes;
• (h) whereby when said device has been rendered conductive between said first and second main electrodes and said appropriate main bias is removed from said first and second main electrodes, opposite type conductivity carriers in said third region are rapidly transferred to said first region by being attracted toward and into said second region, causing said second region to efficiently inject opposite type conductivity carriers into said first region where said injected opposite type carriers combine with one type conductivity carriers in said first region to rapidly turn said device off.