US Patent 7102179 Power semiconductor device used for power control

A power semiconductor device includes a first semiconductor layer, a second semiconductor layer of a first conductivity type, first and second main electrodes, a control electrode and a third semiconductor layer. The second semiconductor layer is formed on the first semiconductor layer. The first and second main electrodes are formed on the second semiconductor layer separately from each other. The control electrode is formed on the second semiconductor layer between the first and second main electrodes. The third semiconductor layer is formed on the second semiconductor layer between the control electrode and the second main electrode.