US Patent 9219136 Switching element

Provided is a switching element that is hardly destroyed even under a high bias condition in an off state because an electric field near a gate electrode is relaxed. A switching element 1 includes a carrier transit layer 13, a carrier supply layer 14 formed on an upper surface of the carrier transit layer 13, having a wider bandgap than the carrier transit layer 13, and forming a heterojunction with the carrier transit layer 13, a source electrode 15, a drain electrode 16, and a gate electrode 17 arranged between the source electrode 15 and the drain electrode 16. An impurity-doped layer 20 is interposed between the carrier transit layer 13 and the drain electrode 16. The impurity-doped layer 20 is formed as a semiconductor layer by heavily doping an impurity having the same conductivity type as a carrier constituting a two-dimensional carrier gas layer 18 generated due to the heterojunction, and a depletion layer 23b is formed in the impurity-doped layer 20 when the switching element 1 is in the off state, and thereby a high electric field generated near the gate electrode 17 is dispersed.