Patent ID: 7352008

Claim:
A field effect transistor, comprising: a heterostructure including a buffer layer or substrate with a channel arranged on the buffer layer or substrate as well as with a capping layer arranged on the channel, wherein the channel consists of a piezopolar material having two different type piezocharges and either the region around the boundary interface between the buffer layer or substrate and channel or the region around the boundary interface between the channel and capping layer but not both regions is doped in a manner such that only one type of the piezocharges occurring at the respective boundary interface is compensated, characterized in that on that surface of the capping layer distant to the channel there are arranged two contact electrodes and a gate electrode, and in that the buffer layer or substrate includes GaN, the channel includes InGaN, and the capping layer includes GaN or AlGaN, wherein either the region around the boundary interface between the buffer layer or substrate and the channel is n-doped or the region around the boundary interface between the channel and the capping layer is p-doped.